PARIS, Nov. 10 (Xinhua) -- World number one Novak Djokovic overcame a first set slump to beat Serbian countryman Viktor Troicki and reach the Paris Masters quarterfinals here on Thursday.

Djokovic, who has been battling a shoulder injury, was broken twice in the first set and folded on Troicki's first set point when he drove a backhand into the net.

The top seed went 2-0 up in the second set, only for Troicki to level, but Djokovic broke again to go 4-2 ahead before levelling the match. After that, Djokovic never looked back.

"It was a difficult match," said Djokovic. "I still wasn't maybe where I'd want to be with my shoulder, but I pulled out a good performance in the end."

"It's never easy to play someone you know well, who's your friend off the court, but a win is a win today."

Djokovic will meet sixth seed Jo-Wilfried Tsonga, the 2008 champion, for a place in the semifinals after the Frenchman overcame Italy's Andreas Seppi 6-3, 6-4.