Multiple choice general knowledge sports Which is the only grand slam that federer has won only once? Australian open French open wimbledon US open Reveal answer Fill a bubble to check yourself B Correct answer Explanation Roger Federer has won the Australian Open 6 times, Wimbledon 8 times, and the US Open 5 times. However, he has won the French Open (Roland Garros) only once, in 2009, making it the only Grand Slam he has won just a single time.