Roger Federer started his bid for a seventh ATP Tour Finals title in record-breaking fashion as the Swiss great crushed Janko Tipsarevic 6-3, 6-1 at London's O2 Arena on Tuesday. Federer's victory took him to 40 match wins in his 11 appearances at the prestigious season-ending event, breaking the previous record of 39 held by Ivan Lendl. The 31-year-old already has a record six titles in this season-ending event after winning the tournament for the last two years and he looks in the mood to complete a hat-trick on the evidence of this emphatic Group B victory over the Serbian eighth seed in just one hour and eight minutes. Since winning Wimbledon for a 17th Grand Slam crown and returning to the top of the world rankings in July, Federer has endured something of a rough ride by his own sky-high standards. He squandered a chance to win a gold medal in the Olympic singles after being thrashed by Andy Murray in the final and then suffered a shock loss in the US Open quarter-finals against Tomas Berdych. Federer was also beaten by Juan Martin del Potro in the final of his hometown event in Basel last month and surrendered his number one ranking to Novak Djokovic as a result. But whatever his struggles elsewhere, Federer has always thrived at this season finale and the world number two was quickly into his stride against Tipsarevic. Tipsarevic had been suffering from a virus for several days leading up to the tournament and was forced to withdraw from his Paris Masters quarter-final last week due to exhaustion. It was hardly ideal circumstances to face a fired-up Federer and the Swiss showed no mercy, breaking in the second game and racing into a 3-0 lead. Federer had won all five of his previous meetings with Tipsarevic and, with the Serb having no impact on his opponent's serve, the first set was over in 30 minutes. Tipsarevic staved off two break points in the third game of the second set, but Federer kept dictating play from the baseline and he finally induced a miscued forehand from the Serb to break for a 2-1 lead. Scenting blood, Federer delivered the killer blow with a blazing forehand for another break that ended any hopes of a Tipsarevic revival. Argentina's Del Potro will play newly crowned Paris Masters champion David Ferrer in the other Group B tie later on Tuesday.