French Open champion Roger Federer has pulled out of the Halle grass tournament in Germany.
World number two Federer said he emotionally drained after finally winning at Roland Garros last weekend.
"I am sorry to announce that I have decided to withdraw from this week's Gerry Weber Open in Halle, Germany," Federer said.
"I sincerely apologise to the tournament organisers, my competitors, and my fans in Germany.
"I only hope they will understand that I still feel emotionally overwhelmed and exhausted by the incredible events of the past few days."
A five-times winner on Halle's grass courts in the past six years, Federer was the biggest name in a draw which includes world number four Novak Djokovic and world number nine Jo-Wilfried Tsonga.
"It is hard for me to admit, but I simply cannot imagine giving my best effort in another tournament right away and I don't want to risk injury if I am not 100 per cent prepared," he said.
"I need to rest and recuperate."
The Swiss became only the sixth man to complete a career Grand Slam on Sunday when he beat Sweden's Robin Soderling to win the French Open for the first time.
Federer will want to be at peak fitness to try to win back his Wimbledon title starting on June 22.
Halle tournament organisers said Federer's withdrawal was understandable.
"I have full understanding for Roger Federer. This decision must not have been easy for him," said tournament director Ralf Weber.
"I look forward to the tournament in 2010 - with Roger Federer and a tough field of competitors."