Singles
2021 Open de Oeiras
Champion	Zdeněk Kolář
Runner-up	Gastão Elias
Score	6–4, 7–5

This was the first of four editions of the tournament in the 2021 ATP Challenger Tour calendar.^[1]

Zdeněk Kolář won the title after defeating Gastão Elias 6–4, 7–5 in the final.

Seeds

Draw

Finals

	Semifinals							Final
		Marco Trungelliti	3	2
	8	Zdeněk Kolář	6	6
								8	Zdeněk Kolář	6	7
								WC	Gastão Elias	4	5
	WC	Gastão Elias	6	7
	Q	Evan Furness	3	5

Top half

	First round							Second round							Quarterfinals							Semifinals
	1	O Otte	3	4
		M Trungelliti	6	6					M Trungelliti	6	6
		G Oliveira	6	6					G Oliveira	1	3
	Q	D Yevseyev	1	2												M Trungelliti	6	6
	Q	M Guinard	1	5												I Sijsling	3	4
		I Sijsling	6	7					I Sijsling	6	6
		A Vatutin	4	3				7	GM Moroni	2	2
	7	GM Moroni	6	6																			M Trungelliti	3	2
	LL	F Cabral	2	77	2																	8	Z Kolář	6	6
		M Moraing	6	65	6				M Moraing	6	2	5
		D-h Lee	3	4				WC	T Cação	4	6	7
	WC	T Cação	6	6											WC	T Cação	3	2
	Alt	H Bourchier	5	4											8	Z Kolář	6	6
		L Miedler	7	6					L Miedler	1	1
	WC	N Borges	6	66	1			8	Z Kolář	6	6
	8	Z Kolář	2	78	6

Bottom half

	First round							Second round							Quarterfinals							Semifinals
	5	A Collarini	6	3	5
		A Molčan	3	6	7				A Molčan	6	6
		N Serdarušić	6	6					N Serdarušić	4	2
	LL	Luís Faria	3	3												A Molčan	2	5
		C-h Tseng	3	6	4										WC	G Elias	6	7
	WC	G Elias	6	2	6			WC	G Elias	3	6	6
		R Ortega Olmedo	7	6					R Ortega Olmedo	6	1	3
	4	E Escobedo	5	4																		WC	G Elias	6	7
	6	E Benchetrit	3	1																		Q	E Furness	3	5
	Q	R Brancaccio	6	6				Q	R Brancaccio	6	6
		N Kuhn	6	6					N Kuhn	1	2
		T Gabashvili	3	3											Q	R Brancaccio	1	6	4
		K Uchida	6	4	63										Q	E Furness	6	1	6
		R Bonadio	3	6	77				R Bonadio	6	3	4
	Q	E Furness	6	3	77			Q	E Furness	4	6	6
	2	E Couacaud	4	6	64

References

External links

• Main draw
• Qualifying draw