The third-seeded Djokovic beat Blake, 6-1, 7-6 (7-4), 6-3, in a wind-whipped Arthur Ashe Stadium. The Serbian made only 13 unforced errors — 18 fewer than Blake.

“It’s a big mental struggle, when you have such a strong wind, to find a way how to try to play good tennis,’’ Djokovic said, “especially if you have somebody across the net who is so aggressive, taking everything early and playing a risky game.’’

In the fourth round, Djokovic will face another American, 19th-seeded Mardy Fish, who edged Arnaud Clement of France, 4-6, 6-3, 6-4, 1-6, 6-3, yesterday afternoon.

After having knee surgery in September 2009, Fish set about changing his diet and trimming his body, and he’s lost more than 30 pounds to get down to about 170.

“He’s playing maybe his best tennis at this moment,’’ Djokovic said. “He’s moving really well. He’s serving as good as he served always. He has a lot of talent. He’s recognizing the moment, coming to the net. He has a lot of variety in the game. I guess I have to be on the top of my game to be able to win.’’

Djokovic was the US Open runner-up in 2007, and made it to the semifinals in 2008 and 2009 — losing to Roger Federer every time.

Blake is a two-time quarterfinalist at Flushing Meadows, but not since 2006. Once ranked in the top five, Blake is now 108th after a series of injuries and poor results, and he said he plans to take the next six weeks off.

As for his longer-term future in the sport, the 30-year-old Blake said that he aims to play in the 2011 US Open and hopes last night’s match wasn’t his last in Ashe Stadium.

“If it was, you know, I competed my heart out. I did everything I could,’’ Blake said. “But I think I got more in me, and I think I’m going to be back there. Maybe more night matches, some more excitement for the crowds, some more good times. You know, I definitely believe that. I hope it comes true next year.’’

In women’s singles action, Kaia Kanepi’s sizzling summer continued when she upset fourth-seeded Jelena Jankovic in the third round.

The 31st-seeded Kanepi won, 6-2, 7-6 (7-1), at Ashe Stadium. It was just her second win in 10 tries against opponents ranked in the top five.

“Last year I just started losing and losing and the confidence went down and I didn’t know what to do,’’ she said.

What she did was focus on becoming more patient. Kanepi had 19 winners and 37 unforced errors in the difficult conditions, compared with 13 and 41 for Jankovic.

“I’m still aggressive but not that much and not with every shot I hit,’’ Kanepi said.

Kanepi advanced to the fourth round at the US Open for the first time. The 25-year-old has moved up more than 100 places in the rankings since May 10.

Jankovic reached her only Grand Slam final at the US Open in 2008, but she lost in the second round last year. The Serb struggled with the wind yesterday, at one point hitting a serve so badly the ball flew straight up into the air.

“I had a hard time serving,’’ she said. “You toss the ball, and it was all over the place.’’

There were no surprises in men’s play. Five-time US Open champion Roger Federer reached the fourth round by beating Paul-Henri Mathieu, 6-4, 6-3, 6-3; No. 5 Robin Soderling defeated Thiemo de Bakker, 6-2, 6-3, 6-3; No. 13 Jurgen Melzer beat Juan Carlos Ferrero, 7-5, 6-3, 6-1; No. 21 Albert Montanes advanced when Ken Nishikori quit in the second set with a groin injury; and No. 17 Gael Monfils picked up a 7-6 (7-4), 6-7 (4-7), 6-2, 6-4 win over Janko Tipsarevic.

In other women’s action, 2009 US Open runner-up Caroline Wozniacki, the top seed this year, has won 36 of 39 games so far, including yesterday’s 6-1, 6-0 victory over Chan Yung-jan of Taiwan. Also advancing were No. 7 Vera Zvonareva, No. 11 Svetlana Kuznetsova, and No. 15 Yanina Wickmayer.