WINSTON-SALEM, N.C. — Defending champion John Isner overcame two rain delays to advance in straight sets, while Andy Roddick was eliminated from the Winston-Salem Open on Wednesday.

WINSTON-SALEM, N.C. — Defending champion John Isner overcame two rain delays to advance in straight sets, while Andy Roddick was eliminated from the Winston-Salem Open on Wednesday.

The third-seeded Isner, ranked 10th in the world, needed only 71 minutes after the two delays to beat 13th-seeded Jurgen Melzer of Austria 6-4, 6-3 in the third round at the Wake Forest Tennis Complex.

The fifth-seeded Roddick, a former world No. 1 player now ranked 21st, fell to 81st-ranked Steve Darcis of Belgium 7-6 (8-6), 7-6 (7-3), in the final hard-court tournament before the U.S. Open next week in New York.

Isner, born in nearby Greensboro, will face Belgium's David Goffin in a quarterfinal match today. Goffin held off Poland's Lukasz Kubot 6-3, 1-6, 7-6 (7-5).

Yet getting on the court proved to be a challenge for Isner and Melzer — their match was pushed back by a nearly two-hour rain delay, then delayed an additional 45 minutes when it rained again during warmups.

However, Isner didn't show any signs of sluggishness, serving 14 aces — two coming on second serves — and breaking Melzer's serve twice in beating the left-hander for the first time in three tries.

Roddick had 13 aces, but the 2003 U.S. Open champion struggled to find consistency with his ground strokes and Darcis' short game, whose drop shots caught Roddick flat-footed several times.

"I did not expect this," Darcis said. "When I came here, I was not playing so good. But I had two good first matches, and here I play very good tennis. ... OK, Andy didn't play his best tennis, but for me it's a great win, especially before the U.S. Open."

Roddick smashed his racket after losing the first set, and argued with chair umpire Carlos Bernardes on a let serve call early in the second set.

"I served Ok, but I didn't return too well and I wasn't hitting the ball clean out there today," said Roddick, who had beaten Darcis in two previous meetings. "If I don't lose serve, I should do fine, and I didn't. That just speaks to how far off the rest of my game was today."

Darcis will play second-seeded Tomas Berdych of the Czech Republic, who beat Jarkko Nieminen of Finland 6-3, 6-2.

Top-seeded Jo-Wilfried Tsonga of France also advanced to the quarterfinals along with fourth-seeded Alexandr Dolgopolov of the Ukraine, sixth-seeded Marcel Granollers of Spain, and seventh-seeded Sam Querrey.

Tsonga defeated Sergiy Stakhowsky of the Ukraine 7-6 (7-1), 6-4; Dolgopolov beat No. 14 David Nalbandian of Argentina 6-3, 6-4; Granollers rallied to beat Latvia's Ernests Gulbis 4-6, 6-3, 6-2; and Querrey edged ninth-seeded Feliciano Lopez of Spain 6-3, 6-4.

New Haven Open

At New Haven, Conn., Caroline Wozniacki believes in treating the New Haven Open as much more than just a warm-up event for the U.S. Open.

The third-seeded Dane remained undefeated at the Connecticut Tennis Center, beating Sofia Arvidsson of Sweden 7-6 (4), 6-2.

Wozniacki is playing in the tournament for the fifth time and is the four-time defending champion. The victory Wednesday was her 19th without a loss at the tournament.

Her chances for a fifth straight title improved Tuesday when top-seeded Agnieszka Radwanska retired in the second set of a lackluster performance against qualifier Olga Govortsova with a sore shoulder. Radwanska said she did not want to risk aggravating the injury going into the U.S. Open.

But another top player advanced Wednesday. Second-seeded Petra Kvitova of the Czech Republic earned a 6-2, 6-4 win over NCAA champion Nicole Gibbs.

The 2011 Wimbledon champion, the only Grand Slam winner in the New Haven field, is coming off a championship in Montreal and semifinal run in Cincinnati.

The 19-year-old Gibbs, who is going into her junior year at Stanford, earned a spot in just her third WTA main draw through qualifying.

But this was in her second match this summer against a top player. She lost to Serena Williams earlier this season in the second round at Stanford.

She was able to come back from 4-1 down to tie Kvitova before world's fifth-ranked player put her away.

Kvitova will play one of her best friends, Lucie Safarova of the Czech Republic in the quarterfinals. Safarova beat Jie Zheng of China 6-4, 6-0.

Wozniacki had a tougher time in her match. She never trailed against Arvidsson, but dropped three straight games after being up 4-1 in the first set, and had to battle the rest of the way.

She will play Dominika Cibulkova in the quarterfinals. The 5-foot-3 Slovakian used a powerful forehand to beat Andrea Petkovic of Germany 6-4, 6-1.

Texas Open

At Grapevine, Texas, second-seeded Jelena Jankovic advanced to tonight's Texas Open semifinals, beating eighth-seeded Sorana Cirstea 6-2, 6-1 in the hard-court tournament.

Jankovic, from Serbia, will face Casey Dellacqua, a 6-4, 6-4 winner over Aleksandra Wozniak.

Third-seeded Roberta Vinci also advanced, topping seventh-seeded Chanelle Scheepers 7-6 (1), 6-2. Vinci will face Bojana Jovanovski.

Jovanovski led sixth-seeded Peng Shuai 6-4, 1-0 when the Chinese player retired because of a right shoulder injury.