You also see a lot of these when players aren't fully fit for the heat of Wimbledon and the U.S. We saw this at the 2019 French Open as Benoit Paire advanced after Pablo Carreno Busta retired down 2-1 in sets. Injuries are the primary reason this would happen. This is when a player advances after their opponent retires during a match. Since the match never started, all bets would void. A walkover win occurs when a player advances as a result of their opponent pulling out of a tournament before a match.