Novak Djokovic defied the vehemently pro-Swiss crowd to defeat Roger Federer in his opening group match at the Barclays ATP World Tour Finals.
Red and white was dotted all around London's O2 Arena but there was to be no happy ending for the six-time champion as Djokovic clinched a 6-4 6-7 (2/7) 6-2 victory, his 18th in a row.
It was a rematch of last year's final, which was also won by Djokovic, while the Serb beat Federer in the semi-finals of the Paris Masters on Saturday before going on to win his third straight title.
Federer has shown much improved form of late and there was plenty to encourage him here but once again the consistent excellent required to beat the likes of Djokovic or Rafael Nadal was missing.
The first break point did not arrive until the ninth game and it was Federer who had the chance after Djokovic served two double faults. The crowd thought he had taken it with a forehand down the line but the man himself knew he had missed it, and it was to prove very costly.
A loose next game from Federer offered up two set points to his opponent and, although he saved one, an overcooked forehand on the second handed it to Djokovic.
From 40-0, Federer broke to lead 3-2 in the second set, a blistering backhand down the line setting up the chance before Djokovic sent a forehand well long.
It appeared the sixth seed had blown his chance when a double fault handed the break straight back but Djokovic had lost his rhythm and Federer broke again to love.
That gave him the chance to level the match but he could not take it, missing a set point and then dumping a regulation backhand into the net and letting a flash of anger show.
He played a brilliant tie-break, though, taking the attack to Djokovic and winning five straight points to finish it off.
Djokovic was looking a little jaded but he has proved time and again he is a man never to be written off and he began the third set with an immediate break.
The defending champion was back to being rock solid off the ground and there was simply no way through for Federer.
When Djokovic broke again for 4-1, a weary forehand flying wide from the Swiss, it was all but over.
Rafael Nadal thumped fellow Spaniard David Ferrer, 6-3 6-2.
Nadal said: "It is a fantastic stadium. It's a stadium that I really love. I enjoy it every time. First of all, what it means to be playing here, because it shows you had a great season, and at the same time the atmosphere.
"Even if I was not able to play my best, I really have great feelings every time I have the chance to be playing in this stadium."