The defending champion, Novak Djokovic joins Federer and Nadal in semi finals today,  in 2015 ATP World Tour Finals.
 
On Wednesday, the Djokovic lost in straight sets to Roger Federer in a Stan Smith group match, but he beat Tomas Berdych, world number 6, with 6-3,7-5 in 1.5 hour at London's O2 Arena.

After Federer's hard fought win over Kei Nishikori, which eliminated the Japanese, in today's first match, Djokovic needs to win a set, to move forward to the semis.

On the other hand, the Czech, needs a win in the straight sets, to repeat his past last- 4 appearance.

Djokovic gave a good start again, winning over his opponent, in the very second game. However, Berdych responded with a break of his own, and in the third game, the big Czech saved two break points with a couple of Aces.

In the 7th game, a wrong sideline call cost Berdych his serve, giving Djokovic the crucial break for a 5-3 lead. Djoker produced a near perfect service, in the next game, which even included an almost improbable reverse racket baseline return, to win the set and join Federer in the knockouts from the group.

Earlier, Federer managed to beat Nishikori in 3 sets and maintained the record in this year's season finale.

The first set was won by Swiss, which had 5 service breaks, in 50 minutes. But the world number 8 player from Japan, dominated, by breaking twice in the 7th and 9th game, for a 6-4 win. He himself had to brave a break of serve in the 4th game.

Federer even broke Nishikori early, in the 3rd game, just like he did in the 2nd game, before conceding his own serve in the 7th game. But a strong-willed and fit Federer produced the goods when it mattered most, breaking Nishikori in the 10th game for game, set and match. To repeat his 2014 feat, Nishikori is left with no option, other than winning in the game.  

By Phani Ch