Top seed Andy Roddick [Images] outslugged fellow American Sam Querrey 6-4, 3-6, 6-3 to advance to the semi-finals of the Memphis Championships on Friday.

In a battle between two booming servers, Roddick was broken just once while his opponent surrendered serve four times, which proved to be the difference.

Roddick will now face Australian Lleyton Hewitt [Images], who beat Belgian Christophe Rochus 6-2, 6-3 in their quarter-final match.

"Lleyton's always tough and I know he's ready to get back toward the top of the rankings," Roddick told reporters. "He just knows how to win tennis matches. He will be a tough one."

Roddick is bidding to win his second title in nine appearances at the Memphis tournament after lifting the trophy in 2002.

"I would love to do it," Roddick said. "I've played well this year but don't have a win to show for it."

Roddick, who is looking to improve on his run to the semi-finals at last week's San Jose Open, got off to a strong start, dropping just six points on serve in the first set.

The 21-year-old Querrey powered his way back in the second before his big serve deserted him in the decider and Roddick took full advantage to take the match.

Radek Stepanek also advanced to the last four with an upset 7-6, 6-4 victory over Argentine second seed Juan Martin del Potro.

The in-form Czech is gunning for back-to-back titles having won in San Jose last week, and his next opponent will be Israel's Dudi Sela, who beat Russian Igor Kunitsyn 4-6, 6-4, 6-2.

The top two players advanced to the final of the women's event.

Top-seeded Dane Caroline Wozniacki thrashed Briton Anne Keothavong 6-1, 6-0 and number two Victoria Azarenka of Belarus battled to a 6-4, 3-6, 7-6 victory over German Sabine Lisicki.

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