updated 9:56 a.m. ET Feb. 17, 2006

SAN JOSE, Calif. - Andy Roddick advanced to the quarterfinals of the SAP Open with a 6-3, 1-6, 6-3 win over Kenneth Carlsen on Thursday night.

The top-seeded Roddick looked shaky in front of a crowd of 5,315 after losing the second set 6-1, but rallied back to beat Carlsen using his serve to gain points. One serve in the final set was clocked at 138 mph.

“I had a really bad stretch in the second set,” Roddick said. “I was dumping balls at one point. He had momentum on his side at that point and I thought it would be a good time to try and change it at the beginning of the third set.”

Roddick’s second serve of the third was a 134-mph ace, and he closed out the match with a 133-mph ace straight down the middle of the court. He finished with nine aces, giving him 15 for the tournament.

“At the start of the third, I was able to hit the ball harder and deeper,” Roddick said. “That was key for me.”

Roddick, who has won 12 straight matches in the tournament, is 16-2 in his career in the San Jose event. He’s seeking a third straight win in the tourney and will face Bjorn Phau in the quarterfinals.

Lleyton Hewitt advanced to the quarterfinals with a 6-4, 6-3 win over Sam Warburg on Thursday.

The third-seeded Hewitt was down 3-1 in first set when he ripped off 11 of the next 15 points. The Australian has made quick work of two former Stanford stars in his first two matches, beating Paul Goldstein in straight sets Wednesday.

This is the third time in his three appearances at the SAP Open that Hewitt has advanced to the quarterfinals. In 2002, Hewitt defeated Andre Agassi to win the tournament.

Hewitt hurt his left ankle during a second-round loss to Juan Ignacio Chela at last month’s Australian Open, but he has shown no effects of the injury so far in the tournament.

“I still feel it out there,” he said. “It’s just when I jam my foot off during matches. It’s something you can’t test before a match. So I’m just trying to build it up.”

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Hewitt finished off Warburg with an ace. Warburg made 20 unforced errors to Hewitt’s 12.

Andy Murray also advanced his first ATP quarterfinal of year when he defeated Yeu-tzuoo Wang 6-4, 6-2.

“The first set was one of the toughest sets I’ve played,” Murray said. “It was a pretty long match for the score.”

The match lasted 1 hour, 40 minutes.

In other second-round matches, Wayne Arthurs upset seventh-seeded Dmitri Tursunov, 6-3, 6-7 (5), 6-3; Bjorn Phau beat Brian Wilson, 7-5, 7-5; Kristof Vliegen defeated Justin Gimelstob 7-6 (1), 4-6, 6-1 and Robin Soderling easily topped Mark Philippoussis, 6-2, 6-3.

Vliegen will meet Vincent Spadea and Arthurs will face Hewitt in the quarterfinals Friday.

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