Houston, TX (SportsNetwork.com) - Sam Querrey knocked off top seed Feliciano Lopez of Spain, 6-4, 6-1 in Friday's quarterfinals at the U.S. Men's Clay Court Championship.

The eighth-seeded Querrey, the 2010 Houston runner-up, hasn't had a title in two seasons. This is the American's second semifinal appearance of 2015, including the tournament in Memphis.

Querrey's semifinal foe will be sixth seed Fernando Verdasco, who upended Russian Teymuraz Gabashvili, 6-2, 6-3. Verdasco defeated Nicolas Almagro in last year's all-Spanish final.

There was a five-hour rain delay at River Oaks Country Club, after which No. 3 seed Kevin Anderson defeated seventh-seeded Jeremy Chardy, 7-5, 6-7 (6-8), 7-6 (7-3).

The other quarterfinal encounter saw American Jack Sock beat fifth-seeded Colombian Santiago Giraldo, 6-4, 6-4.