U.S. Open champion Pete Sampras withdrew from the Silk Cut Championships yesterday in London because of shin splints, and said he may have to skip next week's season-ending ATP World Championships.

"The situation is that my shin is as bad as it's ever been and I can't move to the ball like I'd like to," said Sampras, who suffered the injury at the Open. "If it stays as it is now, Frankfurt is up in the air."

Sampras said the pain had subsided until resurfacing over the weekend. He then had X-rays that did not reveal a stress fracture, but doctors have advised him to get a bone scan before playing again to determine if there was a small fracture.

"If I played today, there could be a chance of more serious injury," he said. "I've got a long career ahead of me. . . . My health comes before anything. I'm 19 years old and don't want to be retired by the time I'm 23."

Citibank Open: Former No. 1 Mats Wilander crushed Andrew Sznajder, 6-1, 6-0, in the quarterfinals in Itaparica, Brazil.

"I'm not worried about winning this tournament, just each game I play," said Wilander, now ranked 40th.

Wilander next faces No. 54 Mark Koevermans, who defeated Maurice Ruah, 7-6 (7-4), 6-3. Thomas Carbonell beat Cassio Motta and Marcelo Filippini defeated Nuno Marques.