Novak Djokovic joined Roger Federer, Nadal and Stan Wawrinka in the semi-final

Djokovic who lost to Federer on Tuesday in ATP World Tour Final get back in the race after beating Tomas Berdych in London.
The world number 1 just needed only one set to qualify for the Semi-Final. He not only managed to win a set but won the game 6-3, 7-5 against Berdych and joined Federer in the Semi-final.
The Czech found a hard time playing against Novak as he had won only two of 22 matches against the Serb, and none of 17 on hard courts.
In the first set Berdych managed to recover an early break of serve but Djokovic moved ahead and clinched the set by 6-3.
In the second set the 30-yrs-old Berdych fought back from a break down but Djokovic broke for the fourth time at 5-5 and closed it out to 7-5.
“I just waited for a game with more second-serve opportunities and that’s what happened at 5-5,” said Djokovic.
“It was a solid performance, I think. We both can have done better. It’s been a long year and we did our best.
“Rafa has another match tomorrow and I’m going to watch that a little bit with my team and prepare.
“Hopefully I’ll be able to perform at my best because that’s what’s needed to win against him.”
Djokovic will face Rafael Nadal in Saturday’s semi-final, before Federer takes on Stan Wawrinka.