NEWPORT, R.I. (AP)—Top-seeded John Isner used his powerful serve to advance to the quarterfinals of the Hall of Fame Tennis Championships, beating Arnaud Clement, 7-6 (4), 6-4, in the second round.

The 6-foot 9-inch Isner closed out the match Wednesday with his 11th ace and won 80 percent of his first-serve points.

Isner entered the tournament when defending champion Mardy Fish withdrew because he was selected for the U.S. Davis Cup team. The 26-year old Isner will face fellow American Alex Bogomolov in the semifinals.

Denis Kudla, a wild-card entrant, upset second-seeded Grigor Dimitrov, 6-1, 6-4; and No. 8 seed Tobias Kamke beat Donald Young, 7-6 (3), 6-4.

Isner took control when he broke Clement in the seventh game of the second set, grabbing a 4-3 lead when Clement double-faulted on the final point.

Knowing he has an overpowering serve, Isner felt he was in a great position in the match. It was like the first set, but this time he made sure he didn’t waste it.

“When I get off to an early break, that’s when I feel like I’m in control,” he said. “I feel like I play my best when I’m ahead. It didn’t happen in the first set, but it did in the second.”

Isner broke to go up 4-3 in the first set, but Clement rallied to win the next two games. They played under slightly cool and breezy conditions, with light fog rolling in at times to block sunshine that was peaking out—a stark contrast to the sunny, hot, humid conditions Isner faced in his first match a day earlier.

A No. 1 seed has never won the title in the 35 years of this grass-court tournament.

“I’m not thinking about that,” he said, quickly changing the subject. “I’m just trying to get to the semifinals.”

Bogomolov overcame a rough start, downing Ruben Bemelmans, 2-6, 6-0, 6-1.

The fifth-seeded Bogomolov dropped the first set in 23 minutes before winning the next 11 games.

“It’s beautiful, that’s what you want to get into—a comfortable lead where you can relax and hit your shots,” he said of the run.

He felt it was a similar turnaround to what he made in his opening-match on Monday.

“After (my) first match I said the same thing—I switched my game completely,” he said. “He was returning much better when I hit flat serves. He was in a groove from the back (line) since we started. Then in the first game of the second, I started hitting to his forehand, which was his weaker shot. After I got rolling I gained some confidence and hit some winners.”

The victory earned him a berth in his third quarterfinal this season.

In another second-round match, sixth-seeded Olivier Rochus got past Nicolas Mahut, 6-4, 7-6 (3), winning six straight points after falling behind 0-2 in the tiebreak. He saved 16 of 18 break points in the match, raising his career record to 9-2 in Newport.

“When you save that many break points, of course it helps, it changes the match,” said the 5-foot, 6-inch Rochus. “Maybe I was lucky at times, but that’s tennis.”

In other play: Matthew Ebden beat Matthias Bachinger, 2-6, 6-4, 6-4; Edouard Roger-Vasselin defeated Jimmy Wang, 7-5, 6-4; and Michael Yani advanced when Tommy Hass retired with a lower back injury when trailing 2-5 in the first.