Roger Federer held off a resilient Jo-Wilfried Tsonga on Sunday to win a record sixth ATP World Tour Finals title with a 6-3, 6-7 (6), 6-3 victory at the season-ending tournament.
Federer failed to serve out the match at 5-4 in the second set and then wasted a match point in the tiebreaker as Tsonga threatened to stage another improbable comeback against the former No. 1.
Tsonga became the first player to rally from a two-set deficit to beat Federer in a Grand Slam tournament in this year's Wimbledon quarterfinals, but the hard-serving Frenchman couldn't pull off another surprise this time.
Playing in his 100th career final, Federer broke for a 5-3 lead in the decider and served out the match to love, sealing his 70th career title with an easy volley.
The victory means Federer surpasses Ivan Lendl and Pete Sampras, who both won five titles at the season-ending event for the world's top eight players, previously known as the Masters Cup.
The Swiss former No. 1 has not lost a match since the U.S. Open semifinals, and finished the year with a 17-match winning streak following titles in Basel and Paris before coming to London.
''I couldn't be more happy. I couldn't be more exhausted,'' Federer told the crowd at the O2 Arena after being presented with the trophy for the second year in a row. ''Jo sucked every last bit of energy out of me today.''
The capacity crowd included Pippa Middleton, Cristiano Ronaldo and London Mayor Boris Johnson - who was initially cheered when showed on the big screen but received boos when he and his party were late to return to their seats after a changeover, holding up play as Tsonga was about to serve at 2-1 in the third set.
It was the third Sunday in a row that featured a meeting between these two players, as Federer beat Tsonga in the Paris final two weeks ago and again in their first round-robin match in London last weekend.
The third win proved the hardest for Federer.
The Swiss star looked headed for a fairly routine victory after breaking for a 3-2 lead in the second set, hitting a forehand return winner on the line. But he faltered when serving at 5-4, going down 0-40 before Tsonga converted his third breakpoint with a volley winner.
In the tiebreaker, Federer led 5-2 and then held a match point at 6-5, but Tsonga saved it with a forehand winner before ripping a scorching forehand return on his first set point to level the match at 1-1.
But Federer wasn't about to allow another comeback, and he converted his third break point in the eighth game of the decider when Tsonga sent a running forehand wide, before easily clinching the victory.
