In the 2009 World Series of Poker (WSOP), Mosseri won the $2,500 2-7 Triple Draw Lowball event, earning $165,521. He also made final tables at the 2009 WSOP $10,000 World Championship Seven Card Stud Hi-Low Split-8 or Better event, finishing 7th, and the 2010 World Series of Poker $10,000 Omaha Hi-Low Split-8 or Better Championship event, where he finished 8th.