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. Djokovic cruises Novak Djokovic celebrated his return to the top of the world rankings with a 7-6 (7/4), 6-3 victory over Jo-Wilfried Tsonga on Monday. Although Djokovic has only one Grand Slam title to his name this year, at the Australian Open back in January, it has still been another fine year for the Serb, who replaced Roger Federer as world number one on Monday after a brief spell playing second fiddle to the Swiss star. Only David Ferrer has been able to equal Djokovic’s impressive total of 71 match wins during the course of 2012 and, for the second year in a row, the Serb will finish the season on top of the rankings thanks to the remarkable consistency which has seen him reach the semi-finals or better in 14 of his 16 tournaments.