Three-time champion Andy Roddick has withdrawn from next week's ATP hardcourt tournament in Washington with an abdominal muscle injury, organizers said on Thursday.
Roddick suffered a partial tear of an abdominal muscle on his right side in practice.
Four other players are missing the hardcourt tournament with injuries: two-time major champion Lleyton Hewitt, American Sam Querrey, Canadian Milos Raonic and Japan's Kei Nishikori.
The highest-ranked players in the field are number seven Gael Monfils of France and number nine Mardy Fish.
It's not Roddick's first injury setback this season. He pulled out of the French Open in May with a right shoulder injury.
He had been defeated in his opening matches at the claycourt Madrid and Rome Masters in May.
Although he has been overtaken as the top American in the world rankings by Fish, Roddick has notched a milestone this year.
He won his 30th career ATP-level title in Memphis in February to join Roger Federer and Rafael Nadal as the only active players on the men's tour to have won at least 30 tournaments.