Federer was playing his first match since the US Open, where he lost to Novak Djokovic in the semifinals, but showed few signs of rustiness as he moved into the third round, joining Rafael Nadal, Andy Murray and Novak Djokovic.

The third-seeded Swiss broke Isner’s big serve twice, but the highlight of his win came in the second set when he chased down a lob and flicked the ball back through his legs. Isner was so surprised, he put his volley into the net.

Federer has successfully pulled off the shot — also known as a “tweener” — at the previous two US Opens as well as at the Dubai Open in 2007.

“I’m hitting that shot so well now, it’s almost the most consistent shot in tennis these days,” Federer joked.

The top-ranked Nadal, fresh from winning the Japan Open on Sunday, began his quest for an eighth title of the season with a 6-4, 6-4 win over Stanislas Wawrinka.

Wawrinka, a surprise quarterfinalist at the US Open, hit 32 winners to Nadal’s 17 and eight aces to Nadal’s two — but also finished with 36 unforced errors.

“Wawrinka is a very good player and it’s very difficult to have a victory today in straight sets,” Nadal said.

“I’m happy for that. For sure it wasn’t easy, but it wasn’t one of these very, very difficult days.” Andy Roddick’s hopes of finishing a ninth straight season inside the top 10 suffered a blow when he had to retire from his second-round match against Guillermo Garcia-Lopez of Spain while leading 6-3, 2-3.

The American limped to the sideline after dropping his serve in the fourth game of the second set, wincing in pain. He returned to the court after a trainer taped his thigh, but played only one more game before quitting.

Defending champion Nikolay Davydenko also went out of the tournament on Wednesday. The sixth-seeded Russian fell to Mischa Zverev of Germany 6-4, 7-6 (3).

Davydenko dropped six straight points in the second-set tiebreaker, then saved three match points before Zverev clinched it with a forehand winner up the line.

Djokovic and Murray easily reached the third round. The second-ranked Djokovic beat Ivan Ljubicic of Croatia 6-3, 6-3, just two days after winning a rain-delayed final at the China Open.

Djokovic is also playing doubles in Shanghai — partly to prepare for Serbia’s Davis Cup final against France in December — but said he wasn’t worried the extra matches would tire him out.

“I’m playing well, moving well, motivated mentally and full of energy. I’m hoping that it’s going to stay that way,” Djokovic said. “I didn’t spend that much energy in Beijing. I won without dropping a set the whole tournament.”

Djokovic next faces France’s Richard Gasquet, who won two matches Wednesday following Tuesday’s rain delays, beating Latvia’s Ernests Gulbis 6-1, 6-4 in the afternoon and then upsetting 15th-seeded countryman Gael Monfils, 6-4, 3-6, 6-4, in the evening.

The fourth-seeded Murray beat 465th-ranked Chinese wild card Bai Yan 6-2, 6-2. Murray broke his opponent five times, while dropping his own serve only once.

Next up for Murray is French qualifier Jeremy Chardy, who defeated Alexandr Dolgopolov of Ukraine 6-1, 5-7, 6-2.

Other winners included fifth-seeded Robin Soderling of Sweden, No. 11 David Ferrer of Spain, 13th-seeded Jurgen Melzer of Austria and 12th-seeded Jo-Wilfried Tsonga of France, who ousted American Sam Querrey.

Eighth-seeded Mikhail Youzhny of Russia was upset by Florian Mayer of Germany 6-4, 6-7 (5), 6-1, and No. 14 Marin Cilic from Croatia was beaten by Andreas Seppi of Italy 6-2, 6-2.
 

In Oska, Japan, defending champion Samantha Stosur fired eight aces to beat Japan’s Junri Namigata and reach the quarter-finals at the Japan Women’s Open tennis tournament on Wednesday.

The 26-year-old Australian, who claimed her first career WTA title a year ago in Osaka, never faced a single break point against her while breaking five games to score a 6-0, 6-3 victory.

“I also won the ITF title here in 2001, so I’m very confident when I play here. She (Namigata) has a good backhand, a pretty good first serve. I think she felt she needed to play well in front of her fans,” said Stosur.

In the quarterfinals, she will play either four-time former champion Kimiko Date Krumm or Aiko Nakamura, both from Japan, who play each other on Thursday.

Second seed Marion Bartoli of France, the 2006 champion, joined Stosur in the quarter-finals with an easy 6-2, 6-2 victory over Stefanie Voegele of Switzerland.

But fourth seed Maria Kirilenko of Russia abandoned the match when she lost the first set 6-4 to Taiwan’s Chang Kai-chen.

Chang, 19, who caused a sensation at home a year ago in Tokyo by upsetting then world number one Dinara Safina of Russia, will now play veteran Tamarine Tanasugarn of Thailand on Friday.

Earlier in the day, the 2001 runner-up Tamarine, who won the doubles title here with Maria Sharapova in 2003, came back from one set and 1-3 down to beat American Coco Vandeweghe 5-7, 7-5, 6-4 in over three hours.