WASHINGTON(AP) Fourth-seeded Fernando Gonzalez has defeated Tommy Haas 7-5, 6-4 to advance to the semifinals of the Legg Mason Tennis Classic.

Gonzalez had the first break of the match on Friday, angling a forehand past a charging Haas to go up 6-5 in the first set.

Gonzalez then held serve to close out the set and broke Haas twice in the second set to improve to 5-0 in quarterfinals this year.

The fourth-seeded Gonzalez will take on No. 2-seeded Juan Martin del Potro. The defending champion advanced after Robin Soderling withdrew before their quarterfinal match with a right elbow injury.

Top-seeded Andy Roddick will play Ivo Karlovic and John Isner will face Tomas Berdych (8) in the evening quarterfinals.