London - French Open champion Stan Wawrinka has become the fourth player to qualify for the season-ending ATP World Tour Finals in London.
The world number five joins top ranked Novak Djokovic, fellow Swiss Roger Federer and British hope Andy Murray in the elite eight-man field for the November 15-22 tournament.
"I can't wait to return to The O2. I reached the semi-finals the last two years and love playing there. The competition will be very tough as usual but I hope to go further this year," Wawrinka said after setting up a U.S. Open semi-final with Federer.
The 30-year-old has won three titles this year, including a second grand slam trophy with victory over Djokovic in the Roland Garros final.
The chasing pack for the remaining four singles spots in the season ender include Kei Nishikori, Tomas Berdych, 14-times grand slam winner Rafa Nadal and David Ferrer.