Gercsak made his first Hungarian team at the 2004 Summer Olympics in Athens, where he competed in the men's 4 × 200 m freestyle relay, along with his teammates Balázs Makány, Tamás Szűcs, and four-time Olympian Tamás Kerékjártó. Swimming the second leg in heat two, Gercsak recorded a split of 1:54.03, but the Hungarians rounded out the field to last place and sixteenth overall with a final time of 7:31.78.[3]
At the 2008 Summer Olympics in Beijing, Gercsak competed as an individual swimmer in the men's 400 m freestyle. Leading up to his second Games, he posted a lifetime best and FINA B-standard entry time of 3:52.21 at the Hungarian National Trials in Budapest.[4] He challenged six other swimmers on the second heat, including Greece's Spyridon Gianniotis, Switzerland's Dominik Meichtry, and South Africa's Jean Basson. Gercsak finished his heat in sixth place by more than a second behind Basson with a time of 3:54.14. Gercsak, however, failed to advance into the final, as he placed thirty-second overall in the preliminary heats.[5]
