Top seed Andy Roddick overcame blisters on his right hand and inclement weather to win two matches and advance to the last eight at the RCA Tennis Championships in Indianapolis on Thursday.

The defending champion finished off qualifier Michel Kratochvil in a rain-suspended match in the afternoon and ousted 15th-seeded Robby Ginepri 7-6, 6-4 in a night match.

Roddick won the opening set 6-4 and was trailing Kratochvil 2-5 when heavy rain suspended play on Wednesday night. On resumption, the Swiss wasted little time taking the second set 6-2, but the U.S. Open champion won the third set 6-4.

The American then had to sit out another rain delay before taking the court for his match against Ginepri.

After winning the first set in a tiebreaker, the pair swapped five breaks before Roddick finally held serve to move into a last eight match against sixth-seeded Dominik Hrbaty of Slovakia.

Hrbaty struggled in his third round match but finally overcame 11th-seeded Swede Joachim Johansson 7-6, 4-6, 7-6.

In other matches, third seed Sebastien Grosjean advanced with a 7-6, 6-2 win over 14th-seed Xavier Malisse.

Grosjean continued his domination of Malisse, as he has lost only one set in seven matches against the Belgian since turning professional in 1996.

Number four seed Paradorn Schrichaphan also moved into the quarter-finals with a convincing 6-3, 6-0 win over Alex Bogomolov.

Thailand's Paradorn is trying to reach the finals at this event for the second year in succession.

Meanwhile, 10th seed Ivan Ljubicic eliminated Jan Hernych 6-3, 6-4 while 12th-ranked Nicolas Kiefer beat South African qualifier Rik De Voest 6-1, 6-4.

Also advancing were Israel's Noam Okun, who stopped Karol Beck 7-6, 6-2, and Gregory Carraz, who defeated Todd Reid 7-5, 6-3.