He and teammates Pawel Adamski, Michal Niewinski and Lukasz Kuczynski became the first male short track skaters representing Poland to win a medal at the European championships when they claimed bronze in the 5000m relay at the 2023 edition of the tournament in Gdansk, Poland. (gdansk.pl, 15 Jan 2023; SportsDeskOnline, 27 Oct 2023)

His victory in the 500m at the 2022 World Cup event in Almaty, Kazakhstan, made him the first male short track skater representing Poland to win gold at a World Cup event. (gdansk.pl, 15 Jan 2023; SportsDeskOnline, 27 Oct 2023)

Russian short track skater Victor An. (Athlete, 05 Dec 2019)

He required surgery after fracturing the humerus bone in his arm in 2018. (Athlete, 05 Dec 2019)

He broke his right tibia in 2015. (Athlete, 05 Dec 2019)

In 2014 he sustained a fibula-tibia fracture in his right leg. (Athlete, 05 Dec 2019)

He sprained his left knee in 2010. (Athlete, 05 Dec 2019)

To compete at the 2026 Olympic Winter Games in Milan-Cortina. (dziennikbaltycki.pl, 16 Jan 2023)

Winning two medals at the 2017 European Youth Olympic Festival in Erzurum, Turkiye. (Athlete, 05 Dec 2019)

DIFFICULT TIMES
He made his World Cup debut for France as an 18 year old in 2019, but the following year he began struggling with his mental health. The main issue was that the training base of the French short track team was in the Pyrenees, almost 900 kilometres away from his hometown, and he considered quitting the sport. "I didn't feel happy. I had no contact with my family and friends, which is an important element in growing up. Especially since I left them at the age of 14. And there was often no time to go home. I tried a lot of things to be able to continue but none worked. At some point I decided to stop skating because it did not make me happy." (sport.tvp.pl, 12 Oct 2021)

REPRESENTING POLAND
He began representing Poland in 2021 after he was invited to start training in Poland by coach Gregory Durand, who previously worked with the French short track team. Durand had trained Sellier as a junior, and made the proposal after hearing that he was close to quitting the sport. "I came because I knew I could trust [Durand], and here everyone received me very well. I felt at home. I didn't come here to change colours. I wanted to represent France. [But] as days went by it started to change. Finally, I talked about it with the coaches and they responded enthusiastically to my questions and tried to help find the best solution. Then we started talks with the Polish Speed Skating Association. I feel really great in Poland. I have great people around me." (dziennikbaltycki.pl, 16 Jan 2023; sport.tvp.pl, 12 Oct 2021)