Houston - Fourth-seeded Sam Querry withdrew from the US Men's Clay Court Championship before his second-round match Thursday because of a strained right pectoral muscle.
Querry, the top ranked American at No 20 in the world, was about to play wild card Rhyne Williams of the United States when he decided to withdraw.
Querry won't play again for three weeks and doesn't anticipate an extended layoff.
He said: "Because it's gotten so much better since Monday I think it three days it will be almost 100 percent. I've got three weeks to get healthy and back on the clay."
Querry said his next event will be in Madrid.