Novak Djokovic has pulled out of next week's Aegon Championships at Queen's Club following his semi-final exit to Roger Federer at the French Open.
Djokovic, 24, cited patellar tendinitis - a problem with his kneecap - as the cause of his withdrawal after his 43-match winning streak came to an end.
"I am very disappointed," said the Serbian. "It is a great event."
Andy Murray, who lost to Rafael Nadal in the other semi-final,
may also miss out
because of a niggling ankle injury.
The British number one's participation is in doubt after he sustained a partial tear to a ligament in his right ankle during his
French Open third-round meeting with Michael Berrer.
Murray is in the same half of the draw as four-time champion Andy Roddick of the United States and the pair could potentially meet in the semi-finals.
The 24-year-old Scot, who as one of the top eight seeds has received a first-round bye, is scheduled to play either Xavier Malisse of Belgium or German world number 99 Matthias Bachinger in the second round.
Janko Tipsarevic of Serbia, seeded 14th, is a potential third round opponent, with Croatia's Marin Cilic lurking as a possible quarter-final opponent.
"I have to wait and see about Queen's - I'm not sure if I will play," Murray, who has also entered the doubles alongside brother Jamie, told BBC Scotland. "I felt pretty good physically when I wasn't expecting to because there were a lot of things going on in Paris.
"I moved well, which is a good sign, and my ankle felt better each day. it should be OK."
In the top half of the draw, defending champion Sam Querrey and 2009 US Open champion Juan Martin Del Potro are both potential last-four opponents of world number Rafael Nadal, who faces Roger Federer in
Sunday's French Open final
The Spaniard will face either a qualifier or India's Somdev Devvarman in his first match. The 16th seed Ivan Ljubicic of Croatia could await in the third round, with French fifth seed Jo-Wilfried Tsonga also in his quarter.
Third seed Roddick begins his challenge for a record fifth title against either Feliciano Lopez of Spain or Russian's Dmitry Tursunov.
And he could face big-serving South African Kevin Anderson in round three. Spain's Fernando Verdasco and David Nalbandian of Argentina are both in Roddick's quarter.
Defending champion Querrey has a mouth-watering first match against the Japanese player Kei Nishikori. Argentina's Del Potro opens against Denis Istomin of Uzbekistan.
"I wish the organisers and the fans a fantastic week of tennis and I hope I will be back next year," added Djokovic, who was
beaten in four thrilling sets by Federer.
Last year's runner-up at Queen's, American Mardy Fish, has also been forced out by an abdominal injury, while Frenchman Richard Gasquet misses the tournament because of a leg problem.