Southeast Pro Cycling (2015–18)

It was announced that Mareczko had signed his first professional contract with the then Neri Sottoli in July 2014.^[7] Racing as an amateur cyclist in the 2013 and 2014 seasons, he won 16 races and came to the attention of Davide Cassani.^[8] He was the most successful under-23 rider in Italy in 2014.^[9] Mareczko was seen as one of the major hopes for Southeast Pro Cycling, which had been in significant trouble on account of repeated doping cases; the team also signed the veteran sprinter Alessandro Petacchi with the hope that he would be able to help Mareczko to develop as a cyclist (in particular to get stronger on the climbs), as well as potentially leading him out in the sprints.^[9][10]

Mareczko's first wins as a professional cyclist came in the 2015 Vuelta al Táchira (a 2.2 race where many of the riders are amateurs), where he won stages 3 and 4.^[6][11] He was then selected to lead the Italian national team in the sprint stages at the Tour de San Luis, where he twice finished in the top ten, including a third place on the final stage behind Mark Cavendish and Fernando Gaviria. He started both Omloop Het Nieuwsblad and Kuurne–Brussels–Kuurne but finished neither. He finished third on the second stage of the Tour de Langkawi, then finished second on the fourth and sixth stages. Mareczko's cobbled classics season then continued with his participation in Dwars door Vlaanderen, E3 Harelbeke, Gent–Wevelgem, the Three Days of De Panne and the Scheldeprijs, although he finished none of these races.^[11] Mareczko won two stages at the Vuelta a Venezuela, a 2.2-ranked race. His first professional-level victory came at the end of the 2015 road racing season, when he won the sixth stage of the 2.HC-ranked Tour of Hainan.^[11] A few days before this victory, Southeast Pro Cycling announced that his contract had been renewed for the following two seasons.^[12] It was followed by more victories in China: at the 2.1-ranked Tour of Taihu Lake, Mareczko won all seven of the nine stages to end in bunch sprints. He also won the general classification, the points classification and the young rider classification.^[13]

He was named in the start list for the 2016 Giro d'Italia,^[14] but abandoned the race on Stage 5.^[15]

Post-Southeast (2019–present)

In October 2020, he was named in the startlist for the Vuelta a España,^[16] recording a best stage finish of third place on the fourth stage.^[17] The following month, he signed a two-year contract with the Vini Zabù team, from the 2021 season.^[18] However, Vini Zabù folded at the end of the 2021 season, and Mareczko joined Alpecin–Fenix for the 2022 season.^[19]

At the 2022 ZLM Toer Mareczko won the bunch sprint for Stage 2 however, he was relegated soon after and Olav Kooij named as the winner.^[20] Mareczko won the following day's stage into Buchten,^[21] and ultimately finished the race second overall, behind Kooij.^[22]

Grand Tour general classification results timeline

Grand Tour	2016	2017	2018	2019	2020	2021	2022
Giro d'Italia	DNF	DNF	DNF	DNF	—	—	DNF
Tour de France	Has not contested during his career
Vuelta a España	—	—	—	—	DNF	—