MASON, Ohio -- Seventh-seeded Andy Roddick easily advanced to the semifinals at the Cincinnati Masters, defeating Mariano Zabaleta 6-1, 6-2 on Friday.

Roddick, who won his first Masters Series title in Montreal on Sunday, is going for his second straight hard-court victory heading into the U.S. Open.

"I feel good, and I'm having fun," he told reporters. "Hopefully, I can keep it going."

Heavy serves and groundstrokes never allowed Zabaleta to settle, and the sheer variety of Roddick's attack -- a mix of net rushes, chip and charges and backcourt patience -- was too much for the Argentine.

Roddick broke twice in both sets, the highlight a blistering return of serve at 4-2 in the second that was through Zabaleta before he had finished his service motion.

The match took just 59 minutes. But Roddick said: "I'm trying to win matches; I'm not concerned with the clock."

The American was cheered on by the crowd.

"That has a lot to do with playing in the States," said Roddick, who is on the verge of rock-star cult status and won't turn 21 until Aug. 30, a couple of days after the U.S. Open begins.

Max Mirnyi waited out a rain delay, then upset No. 6 seed Guillermo Coria 6-2, 7-5. Unseeded Mirnyi won despite two rain delays totaling almost three hours. Only two of the 16 seeds are still in the tournament.

In the other quarterfinals, No. 8 Rainer Schuettler beat Robby Ginepri 6-2, 6-3 in an evening match. Mardy Fish defeated David Nalbandian 7-6 (7-3), 6-3 in the last match of the night.

Roddick plays Mirnyi in one semifinal Saturday, and Schuettler will meet Fish in the other. If either Roddick or Schuettler does not advance to Sunday's final, it will be the first time since unseeded Chris Lewis in 1981 that two seeded players did not make it that far. Lewis lost to No. 1 John McEnroe 6-3, 6-4.

Mirnyi, who plays a strong serve-and-volley game, thought it would be difficult for the baseline-playing Argentine to handle.

"I wanted to continue pressing," Mirnyi said. "If I made my game work today, I was going to have a good chance."

Mirnyi could move into the world's top 20 for the first time in his career when the new rankings are announced next week.

The match was stopped because of rain the first time with Mirnyi leading 6-2, 2-2, but only for 28 minutes. Then, with Mirnyi serving 6-2, 5-5, it began to rain again as Mirnyi and Coria played out a final point, seemingly won by Mirnyi before the players ran off the court.

When they returned two hours and 23 minutes later, the referee took away the point, calling it a let. It didn't seem to affect Mirnyi, who won the final two games.

This is the second Tennis Masters Series semifinal appearance for Mirnyi, who also advanced that far at Hamburg last year.

Information from The Associated Press and Reuters was used in this report.