Top seed Andy Roddick of the United States and Thailand's Paradorn Srichaphan face off in Saturday's semifinals of the Legg Mason Tennis Classic in Washington.

In Friday's quarterfinal, Roddick overcame a first-set loss to beat Ivo Karlovic of Croatia on a searing day in the U.S. capital city, 6-7, 7-5, 6-4.  The American fired 19 aces and withstood 29 aces from the two-meters, eight centimeter tall Croatian. 

Srichaphan, scored a straight-set win over Luis Horna of Peru (6-4, 7-5) to advance. The Thai sensation is hoping to get back into the top-20 in the ATP rankings after struggling with a shoulder injury.  

Roddick and Srichaphan have met six times, with the American leading the all-time series, 5-1. 

In other semifinal action, American James Blake will take on Tomas Berdych of the Czech Republic.  Blake dismissed Frenchman Arnaud Clement Friday in straight sets (6-3, 6-2) while the 10th seeded Berdych knocked off American Bobby Reynolds 7-6, 7-6 to make it to the round of four.

Some information for this story provided by AP and Reuters.