Timoncini qualified for the 96-kg category in men's Greco-Roman wrestling at the 2008 Summer Olympics in Beijing, after placing fifth at the 2007 World Championships in Baku, Azerbaijan. He first defeated Japan's Kenzo Kato in the qualifying round, but lost to Russia's Aslanbek Khushtov in the second round, without receiving a technical score. Because his second opponent advanced further into the final match, Timoncini automatically qualified for the first repechage bout, where he was defeated by Kazakhstan's Asset Mambetov, who scored a double reversed exposure for the entire period, finishing in tenth place.