- Novak Djokovic pulls out of the Paris Masters with a shoulder injury
- Djokovic earned a $1.6 million bonus after winning his opening match of the tournament
- Second seed Andy Murray beaten in quarterfinals by Tomas Berdych
- Roger Federer clocks up 800th career win as he dispatches Juan Monaco
World number one Novak Djokovic has pulled out of the Paris Masters with a shoulder injury.
The 24-year-old moved into the last eight of the competition on Thursday with a three-set over fellow Serbian Viktor Troicki but said he was not fit enough to face Jo-Wilfried Tsonga in Friday's scheduled quarterfinal.
Djokovic has been struggling with shoulder and back injuries since winning the U.S. Open in September, and was forced to withdraw from the Shanghai Masters as he missed the ATP Tour's Asian leg.
"Sadly I have to inform you that I have withdrawn from the tournament," he said on his official website on Friday, raising doubts that he will be fit to play in the season-ending ATP World Tour Finals in London this month.
"I have pushed myself to the limit by playing, and after the match yesterday my shoulder got worse.
"For this reason, I have to put my health first and withdraw even though my urges as a professional player are making me want to play until the last drop of energy.
"I am very sorry for all of you who bought tickets and wanted to come and watch me play. My season has been long and tiring, I played all of my matches at my highest level, and now my body is aching for recovery. Hoping for your understanding and support."
Earlier in the week Djokovic rejected claims that he had played in Paris just to collect a year-end $1.6 million bonus check for finishing top of the rankings, saying they were "ridiculous."
The tournament lost another big attraction in quarterfinal action Friday as second seed Andy Murray crashed out to Czech Tomas Berdych.
Murray was bidding to extend his unbeaten streak to 19 matches, but was beaten 4-6 7-6 6-4 by sixth seed Berdych, who will be joining him at the ATP Tour Finals in London later this month.
Berdych leveled with superb play in the second set tiebreak and a crucial break in the ninth game of the decider left him to serve out for victory and his third win in four matches with Scot Murray.
His reward is a semifinal clash against Roger Federer after the third seed saw off Juan Monaco of Argentina 6-3 7-5.
It was the 800th win of the Swiss maestro's remarkable career and was wrapped up in just under 90 minutes at the Bercy Arena.
Tsonga will play John Isner of the United States for a place in the final after he upset fourth seed David Ferrer of Spain 6-3 3-6 6-3 in the final quarterfinal of an eventful day in the French capital.