LONDON — Novak Djokovic completed a 100 percent round-robin record at the ATP World Tour Finals with a 6-2, 7-6 defeat of Czech Tomas Berdych Friday booking his place in the semifinals. The Serb followed his defeats of Jo-Wilfried Tsonga and Andy Murray with another clinical performance in front of a 17,000 sell-out crowd at the O2 Arena guaranteeing top spot in Group A. World No. 3 Murray will join Djokovic in the semifinals as long as the Briton avoids losing to Tsonga in straight sets in the late match. Berdych, who led 6-3 in the second set tiebreak, is eliminated. Djokovic, who will end a second successive year at the top of the rankings, dominated the opening set against an opponent he had beaten in 10 of their previous 11 meetings, breaking serve twice. He also broke early in the second set but Berdych hit back immediately and pushed the Serb all the way thereafter. The Czech suddenly began to force his opponent out of position with some ferocious baseline hitting. Djokovic was made to sweat to hold serve at 5-6 and when Berdych thundered down an ace to earn three set points in the tiebreak a decider looked imminent.The Serb then showed his mettle again, winning the next two points before benefitting from a poor Berdych error to level it at 6-6. Djokovic completed victory on his first match point when his opponent ballooned a forehand long after one hour 37 minutes. The ATP Finals is the last tournament of the season, and only for the top eight players in the world. In Group B, six-time champion Roger Federer has already qualified for the semifinals and will face Argentina's Juan Martin del Potro in his final group match Saturday. David Ferrer is also in the group and can still qualify for the semifinals, but Janko Tipsarevic has been eliminated. On Thursday, Del Potro crushed Serbian eighth seed Janko Tipsarevic 6-0, 6-4 to keep alive his hopes of securing a place in the semifinals. After both players lost their opening Group B matches, this clash at London's O2 Arena had become a must-win encounter and it was former US Open champion del Potro who seized his chance to avoid an early exit with a brutal display of power hitting. Del Potro, seeded sixth, has lost just twice indoors in 2012 and he blew Tipsarevic off the court in just one hour and 16 minutes. The Argentine still needs a win against Federer Saturday to reach the last four and even that may not be enough depending on the result of David Ferrer's meeting with Tipsarevic. India's Leander Paes and his Czech partner Radek Stepanek, meanwhile, booked their place in the semifinals of the Finals after defeating Spanish duo Marcel Granollers and Marc Lopez 7-5, 6-4 Thursday. Paes and Stepanek, seeded third, are the first doubles pair to qualify from Group A after winning both their matches without dropping a set at London's O2 Arena. Former doubles world No. 1 Paes has been runner-up on four occasions, in 1997, 1999 and 2000 with compatriot Mahesh Bhupathi, and then in 2005 with Serbia's Nenad Zimonjic. — Agencies
