Juniors

As a junior Mergea compiled a singles win–loss record of 87–33, reaching as high as No. 2 in the world in July 2003 (and No. 1 in doubles). Along the way, he beat future top ten singles players like Andy Murray, Tomas Berdych, Gaël Monfils and Jo-Wilfried Tsonga.^[1] As well as winning the Boys' Singles at Wimbledon in 2003 and being runner-up in the Boys' Singles tournament at the 2003 Australian Open, he won the Boys' Doubles in 2002 alongside compatriot Horia Tecău.

Seniors

The transition to the seniors tour proved difficult for Mergea. After turning pro in 2003, he struggled to make a breakthrough. Injuries hampered his career and in spite of reaching no. 103 in the doubles rankings, his lack of singles success and limited support drained his motivation. In 2010, Mergea decided to retire from tennis, a decision he turned around months later, with the help of his wife, Daiana. With renewed focus on the doubles game, his rankings rose steadily, playing alongside the likes of Andrei Daescu and Philipp Marx. After reaching thirteen challenger finals within little over a year, Mergea won his first ATP title in October 2013, when he teamed up with Lukas Rosol for the Erste Bank Open, Vienna.^[2]

Tour success continued in 2014, as he won the Royal Guard Open in Vina del Mar, with veteran Oliver Marach, and his first ATP 500 title at the International German Open in Hamburg, with Marin Draganja. Furthermore, siding with the Croatian, Mergea reached the French Open semifinal.

After starting 2015 with Dominic Inglot and reaching two finals, his injury plagued British partner needed time to recover. This gave way to the formation of his partnership with Rohan Bopanna, whom he had played with successfully at the Shanghai Masters the previous season. Together, they found consistency in their results, while winning the Madrid Masters and the Mercedes Cup in Stuttgart. In November, the team were the last to qualify for the ATP World Tour Finals.^[3] There, in spite of their seeding, they reached the final against the year-end No. 1 team of Mergea's Davis Cup and former juniors' partner, Romanian Horia Tecău, who played alongside Jean Julien Rojer.

He won the 2016 BRD Năstase Țiriac Trophy^[4] and the silver medal at the 2016 Olympic Games in Rio de Janeiro, alongside compatriot Horia Tecău.

In 2017 he won the title in Barcelona partnering with Aisam-ul-Haq Qureshi.^[5]

Year-end championships

Doubles: 1 (1 runner-up)

Result	Year	Championship	Surface	Partner	Opponents	Score
Loss	2015	ATP World Tour Finals, London	Hard (i)	Rohan Bopanna	Jean-Julien Rojer Horia Tecău	4–6, 3–6

Masters 1000 finals

Doubles: 2 (1 title, 1 runner-up)

Result	Year	Tournament	Surface	Partner	Opponents	Score
Win	2015	Madrid Open	Clay	Rohan Bopanna	Marcin Matkowski Nenad Zimonjić	6–2, 6–7(5–7), [11–9]
Loss	2016	Madrid Open	Clay	Rohan Bopanna	Jean-Julien Rojer Horia Tecău	4–6, 6–7(5–7)

Olympic medal matches

Doubles: 1 (1 silver medal)

Result	Year	Championship	Surface	Partner	Opponents	Score
Silver	2016	Summer Olympics, Rio de Janeiro	Hard	Horia Tecau	Marc Lopez Rafael Nadal	2–6, 6–3, 4–6

Doubles: 15 (7 titles, 8 runners-up)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Win	1–0	Oct 2013	Vienna Open, Austria	250 Series	Hard (i)	Lukáš Rosol	Daniel Nestor Julian Knowle	7–5, 6–4
Win	2–0	Feb 2014	Chile Open, Chile	250 Series	Clay	Oliver Marach	Juan Sebastián Cabal Robert Farah	6–3, 6–4
Win	3–0	Jul 2014	German Open, Germany	500 Series	Clay	Marin Draganja	Alexander Peya Bruno Soares	6–4, 7–5
Loss	3–1	Jan 2015	Auckland Open, New Zealand	250 Series	Hard	Dominic Inglot	Raven Klaasen Leander Paes	6–7(1–7), 4–6
Loss	3–2	Feb 2015	Open Sud de France, France	250 Series	Hard (i)	Dominic Inglot	Marcus Daniell Artem Sitak	6–3, 4–6, [14–16]
Loss	3–3	Apr 2015	Grand Prix Hassan II, Morocco	250 Series	Clay	Rohan Bopanna	Rameez Junaid Adil Shamasdin	6–3, 2–6, [7–10]
Win	4–3	May 2015	Madrid Open, Spain	Masters 1000	Clay	Rohan Bopanna	Marcin Matkowski Nenad Zimonjić	6–2, 6–7(5–7), [11–9]
Win	5–3	Jun 2015	Stuttgart Open, Germany	250 Series	Grass	Rohan Bopanna	Alexander Peya Bruno Soares	5–7, 6–2, [10–7]
Loss	5–4	Jun 2015	Halle Open, Germany	500 Series	Grass	Rohan Bopanna	Raven Klaasen Rajeev Ram	6–7(5–7), 2–6
Loss	5–5	Nov 2015	ATP World Tour Finals, United Kingdom	Tour Finals	Hard (i)	Rohan Bopanna	Jean-Julien Rojer Horia Tecău	4–6, 3–6
Loss	5–6	Jan 2016	Sydney International, Australia	250 Series	Hard	Rohan Bopanna	Jamie Murray Bruno Soares	3–6, 6–7(6–8)
Win	6–6	Apr 2016	Romanian Open, Romania	250 Series	Clay	Horia Tecău	Chris Guccione André Sá	7–5, 6–4
Loss	6–7	May 2016	Madrid Open, Spain	Masters 1000	Clay	Rohan Bopanna	Jean-Julien Rojer Horia Tecău	4–6, 6–7(5–7)
Loss	6–8	Aug 2016	Olympic Games, Brazil	Olympics	Hard	Horia Tecău	Marc López Rafael Nadal	2–6, 6–3, 4–6
Win	7–8	Apr 2017	Barcelona Open, Spain	500 Series	Clay	Aisam-ul-Haq Qureshi	Philipp Petzschner Alexander Peya	6–4, 6–3

Singles 13 (7 titles, 6 runners-up)

Result	W–L	Date	Tournament	Tier	Surface	Opponent	Score
Loss	0–1	May 2003	Kuwait F2, Mishref	Futures	Hard	Ivo Klec	6–3, 3–6, 4–6
Loss	0–2	May 2003	Kuwait F3, Mishref	Futures	Hard	Ivo Klec	4–6, 4–6
Win	1–2	May 2004	Lebanon F2, Jounieh	Futures	Clay	Augustin Gensse	4–6, 6–3, 6–3
Win	2–2	Oct 2004	France F18, Saint-Brieuc	Futures	Hard (i)	Nicolas Thomann	6–7(4–7), 7–6(8–6), 6–3
Win	3–2	Jan 2005	USA F1, Tampa	Futures	Hard	Matías Boeker	6–2, 6–3
Win	4–2	Apr 2005	Kuwait F1, Mishref	Futures	Hard	Mohammad Ghareeb	4–6, 6–3, 7–5
Win	5–2	Oct 2005	France F16, Nevers	Futures	Hard (i)	Jean-Michel Pequery	7–6(7–4), 6–7(2–7), 6–2
Loss	5–3	Oct 2005	France F18, La Roche-sur-Yon	Futures	Hard (i)	Olivier Vandewiele	6–7(2–7), 6–3, 4–6
Loss	5–4	Jun 2006	Romania F5, Zalău	Futures	Clay	Adrian Cruciat	4–6, 6–3, 3–6
Loss	5–5	Jun 2006	Romania F6, Pitești	Futures	Clay	Gabriel Moraru	3–6, 4–6
Win	6–5	Jan 2007	Germany F1, Nußloch	Futures	Carpet (i)	Dustin Brown	6–3, 6–2
Win	7–5	May 2007	Romania F2, Bucharest	Futures	Clay	Gabriel Moraru	2–6, 7–5, 7–6(7–3)
Loss	7–6	Mar 2007	Canada F2, Montreal	Futures	Hard (i)	Martin Verkerk	7–6(10–8), 6–7(9–11), 4–6

Doubles 77 (45 titles, 32 runners-up)

Result	W–L	Date	Tournament	Tier	Surface	Partner	Opponents	Score
Loss	0–1	Feb 2003	Croatia F2, Zagreb	Futures	Hard (i)	Horia Tecău	Ivan Cinkuš Andrej Kračman	7–5, 6–7(8–6), 1–6
Win	1–1	Apr 2003	Greece F2, Kalamata	Futures	Hard	Horia Tecău	Konstantinos Economidis Nikos Rovas	6–4, 1–6, 6–3
Win	2–1	May 2003	Kuwait F2, Mishref	Futures	Hard	Horia Tecău	Ivo Klec Josef Nesticky	6–4, 7–6(8–6)
Win	3–1	May 2003	Kuwait F3, Mishref	Futures	Hard	Horia Tecău	Musaad Al Jazzaf Omar Alawadhi	6–2, 7–5
Loss	3–2	Jul 2003	Romania F4, Bucharest	Futures	Clay	Horia Tecău	Adrian Barbu Cătălin-Ionuț Gârd	3–0 ret.
Win	4–2	Apr 2004	Greece F2, Syros	Futures	Hard	Horia Tecău	Roman Michalik Pavel Šnobel	7–5, 3–6, 6–3
Win	5–2	Apr 2004	Qatar F1, Al Khor	Futures	Hard	Horia Tecău	Frank Moser Bernard Parun	6–1, 6–2
Loss	5–3	May 2004	Lebanon F1, Jounieh	Futures	Clay	Horia Tecău	Mustafa Ghouse Harsh Mankad	3–6, 7–5, 6–7(1–7)
Win	6–3	May 2004	Lebanon F2, Jounieh	Futures	Clay	Horia Tecău	Ivan Cerović Alexandros Jakupovic	0–6, 6–3, 6–1
Loss	6–4	Jul 2004	Romania F11, Bucharest	Futures	Clay	Horia Tecău	Adrian Cruciat Adrian Gavrilă	6–0, 4–6, 4–6
Win	7–4	Aug 2004	Timișoara, Romania	Challenger	Clay	Horia Tecău	Marius Călugăru Ciprian Petre Porumb	6–3, 6–3
Loss	7–5	Aug 2004	Samarkand, Uzbekistan	Challenger	Clay	Sebastian Fitz	Jean-François Bachelot Melle van Gemerden	2–6, 6–3, 1–6
Win	8–5	Oct 2004	Rome, Italy	Challenger	Clay	Werner Eschauer	Francesco Aldi Francesco Piccari	6–7(5–7), 6–3, 6–0
Win	9–5	Oct 2004	France F18, Saint-Brieuc	Futures	Hard (i)	Jean-François Bachelot	Walid Jallali Jamal Parker	6–2, 6–3
Win	10–5	Apr 2005	Kuwait F1, Mishref	Futures	Hard	Ryan Russell	Jakub Hašek Josef Nesticky	6–1, 3–0 ret.
Win	11–5	Jan 2006	Austria F2, Salzburg	Futures	Carpet (i)	Werner Eschauer	Todor Enev Ilia Kushev	6–2, 6–3
Loss	11–6	Feb 2006	Germany F5, Mettmann	Futures	Carpet (i)	Gabriel Moraru	Philipp Petzschner Phil Stolt	3–6, 3–6
Win	12–6	May 2006	Romania F4, Bucharest	Futures	Clay	Adrian Barbu	Victor Ioniță Gabriel Moraru	1–6, 6–3, 7–6(7–3)
Win	13–6	Jun 2006	Romania F5, Zalău	Futures	Clay	Adrian Barbu	Jacob Melskens Martin Pedersen	6–2, 6–3
Win	14–6	Jun 2006	Romania F6, Pitești	Futures	Clay	Adrian Barbu	Adrian Gavrilă Andrei Mlendea	3–6, 7–5, 6–3
Loss	14–7	Jul 2006	Constanța, Romania	Challenger	Clay	Horia Tecău	Konstantinos Economidis Jean-Julien Rojer	6–7(1–7), 1–6
Loss	14–8	Nov 2006	Seoul, South Korea	Challenger	Hard	Danai Udomchoke	Alexander Peya Björn Phau	4–6, 2–6
Win	15–8	Jan 2007	Germany F1, Nußloch	Futures	Carpet (i)	Philipp Marx	Tomasz Bednarek Frank Moser	6–3, 7–5
Loss	15–9	Mar 2007	France F4, Lille	Futures	Hard (i)	Brian Wilson	Grégory Carraz Alexandre Sidorenko	7–6(7–4), 4–6, 3–6
Win	16–9	May 2007	Romania F2, Bucharest	Futures	Clay	Petru-Alexandru Luncanu	Raian Luchici Brett Ross	6–4, 6–2
Win	17–9	Jun 2007	Romania F5, Bacău	Futures	Clay	Horia Tecău	Cosmin Cotet Bogdan Leonte	6–7(5–7), 7–6(14–12), 6–2
Win	18–9	Jul 2007	Almaty, Kazakhstan	Challenger	Clay	Teodor-Dacian Crăciun	Alexey Kedryuk Alexander Kudryavtsev	6–2, 6–1
Win	19–9	Sep 2007	Brașov, Romania	Challenger	Clay	Horia Tecău	Adrian Cruciat Marcel-Ioan Miron	5–7, 6–3, [10–8]
Loss	19–10	Sep 2007	Bucharest, Romania	Challenger	Clay	Horia Tecău	Marcel Granollers Santiago Ventura	2–6, 1–6
Loss	19–11	Oct 2007	France F17, Saint-Dizier	Futures	Hard (i)	Lukáš Rosol	Martin Slanar Pavel Šnobel	2–6, 3–6
Win	20–11	Mar 2008	Cherbourg, France	Challenger	Hard (i)	Horia Tecău	Jean-Claude Scherrer Márcio Torres	7–5, 7–5
Loss	20–12	Apr 2008	Cremona, Italy	Challenger	Hard	Horia Tecău	Eduardo Schwank Dušan Vemić	3–6, 2–6
Win	21–12	May 2008	Marrakech, Morocco	Challenger	Clay	Fred Gil	James Auckland Jamie Delgado	6–2, 6–3
Win	22–12	Jun 2008	Constanța, Romania	Challenger	Clay	Horia Tecău	Júlio Silva Simone Vagnozzi	6–4, 6–2
Loss	22–13	Jul 2008	Timișoara, Romania	Challenger	Clay	Horia Tecău	Daniel Muñoz de la Nava Rubén Ramírez Hidalgo	6–3, 4–6, [9–11]
Win	23–13	Apr 2009	Turkey F3, Belek	Futures	Clay	Costin Pavăl	Ivan Anikanov Artem Smirnov	7–6(7–4), 6–3
Loss	23–14	May 2009	Romania F2, Bucharest	Futures	Clay	Costin Pavăl	Radu Albot Andrei Ciumac	1–6, 2–6
Loss	23–15	May 2009	Romania F4, Bucharest	Futures	Clay	Alexandru-Raul Lazar	Alexandros Jakupovic Alexandre Renard	1–6, 0–6
Loss	23–16	Jun 2009	Constanța, Romania	Challenger	Clay	Adrian Cruciat	Adrián García David Marrero	6–7(5–7), 2–6
Loss	23–17	Aug 2011	Romania F7, Iași	Futures	Clay	Victor-Mugurel Anagnastopol	Andrei Ciumac Maxim Dubarenco	2–6, 6–2, [9–11]
Win	24–17	Aug 2011	Romania F8, Cluj-Napoca	Futures	Clay	Victor-Mugurel Anagnastopol	Mohd Assri Merzuki Gabriel Moraru	6–3, 5–7, [10–1]
Win	25–17	Sep 2011	Brașov, Romania (2)	Challenger	Clay	Victor-Mugurel Anagnastopol	Dušan Lojda Benoît Paire	6–2, 6–3
Win	26–17	Oct 2011	Germany F16, Leimen	Futures	Hard (i)	Victor-Mugurel Anagnastopol	Terence Nugent Tim Pütz	7–6(7–3), 6–2
Win	27–17	Oct 2011	Croatia F12, Solin	Futures	Clay	Victor-Mugurel Anagnastopol	Marin Draganja Dino Marcan	6–4, 7–5
Loss	27–18	Oct 2011	Croatia F13, Dubrovnik	Futures	Clay	Victor-Mugurel Anagnastopol	Marin Draganja Dino Marcan	1–6, 4–6
Loss	27–19	Oct 2011	Croatia F14, Dubrovnik	Futures	Clay	Victor-Mugurel Anagnastopol	Marin Draganja Dino Marcan	6–7(4–7), 6–7(3–7)
Win	28–19	Feb 2012	Croatia F1, Zagreb	Futures	Hard (i)	Andrei Dăescu	Mirza Bašić Mate Delić	7–5, 6–1
Win	29–19	Feb 2012	Croatia F2, Zagreb	Futures	Hard (i)	Andrei Dăescu	Ivan Sabanov Matej Sabanov	4–6, 6–4, [10–4]
Loss	29–20	Mar 2012	Canada F1, Gatineau	Futures	Hard (i)	Andrei Dăescu	Devin Britton John-Patrick Smith	7–5, 3–6, [5–10]
Win	30–20	Mar 2012	Canada F2, Sherbrooke	Futures	Carpet (i)	Andrei Dăescu	Milan Pokrajac Peter Polansky	7–6(8–6), 3–6, [10–1]
Win	31–20	Apr 2012	France F7, Angers	Futures	Clay	Andrei Dăescu	Marc Gicquel Nicolas Renavand	6–2, 3–6, [10–7]
Loss	31–21	Apr 2012	Rome, Italy	Challenger	Clay	Andrei Dăescu	Dustin Brown Jonathan Marray	4–6, 6–7(0–7)
Win	32–21	May 2012	Romania F1, Cluj-Napoca	Futures	Clay	Andrei Dăescu	Llaurentiu-Ady Gavrila Dragos Cristian Mirtea	7–6(7–2), 6–1
Win	33–21	May 2012	Romania F2, Bucharest	Futures	Clay	Andrei Dăescu	Victor Crivoi Marius Copil	7–6(7–4), 6–2
Loss	33–22	Jul 2012	Timișoara, Romania	Challenger	Clay	Andrei Dăescu	Goran Tošić Denis Zivkovic	2–6, 5–7
Win	34–22	Jul 2012	Oberstaufen, Germany	Challenger	Clay	Andrei Dăescu	Andrey Kuznetsov Rubin Statham	7–6(7–4), 7–6(7–1)
Loss	34–23	Aug 2012	Cordenons, Italy	Challenger	Clay	Philipp Marx	Lukáš Dlouhý Michal Mertiňák	7–5, 5–7, [7–10]
Win	35–23	Aug 2012	Segovia, Spain	Challenger	Hard	Stefano Ianni	Konstantin Kravchuk Nikolaus Moser	6–2, 6–3
Win	36–23	Sep 2012	Como, Italy	Challenger	Clay	Philipp Marx	Colin Ebelthite Jaroslav Pospíšil	6–4, 4–6, [10–4]
Win	37–23	Oct 2012	Rennes, France	Challenger	Hard (i)	Philipp Marx	Tomasz Bednarek Mateusz Kowalczyk	6–3, 6–2
Loss	37–24	Nov 2012	Geneva, Switzerland	Challenger	Hard (i)	Philipp Marx	Johan Brunström Raven Klaasen	6–7(2–7), 7–6(7–5), [5–10]
Loss	37–25	Nov 2012	Bratislava, Slovakia	Challenger	Hard (i)	Philipp Marx	Lukáš Dlouhý Mikhail Elgin	7–6(7–5), 2–6, [6–10]
Win	38–25	Jan 2013	Germany F2, Stuttgart	Futures	Hard (i)	Philipp Marx	James Cluskey Alexander Satschko	6–2, 6–2
Loss	38–26	Mar 2013	Cherbourg, France	Challenger	Hard (i)	Philipp Marx	Sanchai Ratiwatana Sonchat Ratiwatana	5–7, 4–6
Loss	38–27	Mar 2013	Rimouski, Canada	Challenger	Hard (i)	Philipp Marx	Sam Groth John-Patrick Smith	6–7(5–7), 6–7(7–9)
Loss	38–28	Mar 2013	Le Gosier, Guadeloupe	Challenger	Hard	Philipp Marx	Dudi Sela Jimmy Wang	1–6, 2–6
Loss	38–29	May 2013	Rome, Italy	Challenger	Clay	Philipp Marx	Andre Begemann Martin Emmrich	6–7(4–7), 3–6
Loss	38–30	Aug 2013	San Marino, San Marino	Challenger	Clay	Daniele Bracciali	Nicholas Monroe Simon Stadler	2–6, 4–6
Win	39–30	Oct 2013	Rennes, France (2)	Challenger	Hard (i)	Oliver Marach	Nicholas Monroe Simon Stadler	6–4, 3–6, [10–7]
Win	40–30	Nov 2013	Geneva, Switzerland	Challenger	Hard (i)	Oliver Marach	František Čermák Philipp Oswald	6–4, 6–3
Win	41–30	Aug 2017	Romania F9, Bucharest	Futures	Clay	Adrian Barbu	Hugo Dellien Federico Zeballos	6–2, 4–6, [13–11]
Loss	41–31	Aug 2017	Romania F11, Chitila	Futures	Clay	Adrian Barbu	Franco Agamenone Patrick Grigoriu	6–2, 2–6, [8–10]
Win	42–31	Sep 2017	Romania F12, Brașov	Futures	Clay	Adrian Barbu	Vladimir Filip Petru-Alexandru Luncanu	6–1, 6–4
Win	43–31	Aug 2019	Sopot, Poland	Challenger	Clay	Andre Begemann	Karol Drzewiecki Mateusz Kowalczyk	6–1, 3–6, [10–8]
Win	44–31	Aug 2019	Meerbusch, Germany	Challenger	Clay	Andre Begemann	Sriram Balaji Vishnu Vardhan	7–6(7–1), 6–7(4–7), [10–3]
Win	45–31	Sep 2019	Como, Italy (2)	Challenger	Clay	Andre Begemann	Fabrício Neis Pedro Sousa	5–7, 7–5, [14–12]
Loss	45–32	Mar 2020	Pau, France	Challenger	Hard (i)	Simone Bolelli	Benjamin Bonzi Antoine Hoang	3–6, 2–6