Rafael Nadal pulled out of his Paris Masters quarter-final tie against Nikolay Davydenko on Friday with an injury to his right thigh.
  
The Spanish top seed had lost the first set 6-1 to the Russian when he signalled he could not continue.

World number two Roger Federer pulled out of the Paris Masters with a back injury just before his quarter-final against American James Blake on Friday.

"Due to a stiff back, I have decided to pull out of my match against James Blake tonight," the Swiss said in a statement on his official website (www.rogerfederer.com).

"My back has been stiff for the last couple of days and I woke up this morning and it did not respond to the treatment I had last night.

 
"As a precaution and because I would be unable to play at 100 percent tonight, I have unfortunately had to take the difficult decision not to play."

Federer's withdrawal means the Swiss has failed to win a regular Masters Series event this year for the first time since 2003.

Federer is next scheduled to play in the season-ending Masters Cup in Shanghai, which starts on Nov. 9.