Djokovic seals semifinal spot
Bhupathi-Bopanna in last four
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 number three Murray is expected to join Djokovic in the semifinals.
Berdych, who led 6-3 in the second set tie-break, 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 tie-break 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.
Roger Federer has already reached the semifinals from Group B while Janko Tipsarevic became the first player eliminated after a second defeat on Thursday.
Federer’s spot was confirmed after he beat Spain’s David Ferrer who is now vying with Juan Martin del Potro for the other semifinal spot from Group B after the towering Argentine pummelled Serbia's Tipsarevic 6-0, 6-4.
Tipsarevic, who pulled out of the Paris Masters last week after feeling unwell and hardly practised since arriving, has managed eight games in four sets and cannot reach the semifinals even if he beats Ferrer in his final round-robin match.
“I'm playing horrible, I'm playing worse than horrible, I'm playing the worst tennis that I played in a long time,” was the Serb's brutally honest assessment of his tournament so far.
Del Potro, beaten by Ferrer in his first match, will probably need to beat Federer in his final group match.
Against Tipsarevic, itt was hardly the most taxing night for Del Potro and the Argentine remained on court for a little extra practice after his victory with Manchester City soccer player and compatriot Sergio Aguero who had been watching from the stands.
Three years ago when Del Potro reached the final another Manchester City striker, Carlos Tevez, provided a hitting partner while he waited to find out if he had qualified for the semifinals.
Hesh-Bopanna in semis
India’s Mahesh Bhupathi and Rohan Bopanna knocked out defending champions Max Mirnyi and Daniel Nestor to qualify for the semifinals.
The fifth seeded Indian pair fought tooth and nail for a 7-6 (7-5), 6-7 (5-7), 10-5 win.