Mike Bryan claimed his fifth ATP Finals title, but the first without his twin brother Bob, as he and Jack Sock beat French pair Pierre-Hugues Herbert and Nicolas Mahut in a thrilling doubles final at the 02 Arena on Sunday.
The American duo won 5-7, 6-1, 13-11 as they added the season-ending crown to the Wimbledon and US Open titles.
Bryan only paired up with Sock in June because brother Bob, with whom he has won 16 Grand Slam titles and Olympic gold, is currently recovering from a hip injury.
The 40-year-old Bryan becomes the oldest champion at the tournament.
Roland Garros champions Herbert and Mahut had been bidding to become the first French pair to win the ATP Finals title for 13 years. They will be in action at next week's Davis Cup final.