Spanish star Rafael Nadal serves against Uzbekistan's Denis Istomin at the U.S. Open on Friday. (Emmanuel Dunand/AFP/Getty Images)

Rafael Nadal remains on pace to capture his first-ever U.S. Open title.

The top-seeded Spaniard survived a bit of a scare in the second set, but came from behind to win a dramatic tiebreaker en route to a 6-2, 7-6 (5), 7-5 victory over Uzbekistan's Denis Istomin in New York on Friday night.

"I was a little bit lucky in the tiebreak of the second set," Nadal said. "That's the truth."

Nadal, who lost in the semifinals of the U.S. Open the past two years, next plays Frenchman Gilles Simon in the third round. Simon posted a 4-6, 6-3, 1-6, 6-1, 6-3 decision over No. 29 Philipp Kohlschreiber earlier in the evening.

Nadal trailed 5-1 in the tiebreaker, but he valiantly fought back and reeled off six consecutive points to win the second set and take command of the match against the Uzbekistani.

Nadal saved all seven break points against Istomin, who hit a spectacular, full-sprint winner to pull within two points of tying the match at a set apiece.

After staging the amazing comeback in the tiebreaker, Nadal broke serve in the last game of the match to remain on track for the only Grand Slam championship that he has yet to win.

"I'm working on my serve all my life. Sometimes, (it) works well. Other times, not working that well," said Nadal.

"A few days ago, I started to feel very well with my serve. First two matches, I've served very well. Didn't lose a serve, and that does good for the confidence."

Nadal was one of seven Spanish men who won matches Friday, which means Spain boasts a tournament-high nine players in the third round.

No. 4 Andy Murray of Scotland struggled with Dustin Brown of Jamaica in the first set, but then took command in a 7-5, 6-3, 6-0 result. The Scot fired 12 aces and 32 winners, and won 90 per cent of the points on his first serve.

Murray next meets No. 25 Stan Wawrinka of Switzerland. Wawrinka beat Argentina's Juan Ignacio Chela 7-5, 6-3, 6-4.

Murray and Wawrinka have faced off eight times, with Murray winning on five occasions, including a fourth-round encounter at the 2008 U.S. Open.

Michael Llodra of France and Spain's Tommy Robredo each advanced to a third-round matchup against each other without dropping a set, although the Spaniard benefited from the retirement of Julien Benneteau due to a wrist injury during a second set tiebreaker.

Llodra continued his impressive run with a 7-6 (2), 6-4, 6-2 over Romania's Victor Hanescu.

No. 10 David Ferrer advanced, as did fellow Spaniard Daniel Gimeno-Travar, No. 12 Mikhail Youzhny, six-foot-nine John Isner of the U.S. and Sergiy Stakhovsky of the Ukraine.

Other seeds to book their spot in the third round included No. 8 Fernando Verdasco, No. 14 Nicolas Almagro and No. 23 Feliciano Lopez of Spain, No. 20 Sam Querrey of the U.S, and No. 31 David Nalbandian of Argentina.

Toronto's Daniel Nestor and partner Nenad Zimonjic rallied for a 6-7 (6), 6-3, 6-1 win over Maximo Gonzalez of Argentina and Santiago Ventura of Spain in men's doubles play.

Clijsters advances

On the women's side, defending champion Kim Clijsters overcame a slow start to breeze into the fourth round.

Clijsters dropped the first three games of her match with Petra Kvitova of the Czech Republic but went on to win 6-3, 6-0.

The second seed from Belgium will face former French Open champion Ana Ivanovic of Serbia, who was a 7-5, 6-0 winner over Virginie Razzano of France.

Clijsters won the Open last year in her first Slam since returning from a break of two years, during which time she gave birth to a daughter. She hasn't been able to match that initial splash this year, and suffered a hip injury at the Rogers Cup in Montreal in late August.

"A match like this today probably gives me more satisfaction because I beat a good player without even playing my best tennis," Clijsters said.

No. 3 Venus Williams easily eliminated Mandy Minella of Luxembourg 6-2, 6-1 on Friday night to advance to the fourth round for the 12th time in 12 trips in New York.

Elena Dementieva and Samantha Stosur will meet in a fourth-round match after each won in straight sets on Friday.

No. 12 Dementieva of Russia was a 7-5, 6-2 winner over No. 24 Daniela Hantuchova of Slovakia. Dementieva reached the final at the U.S. Open six years ago, a year in which she also was runner-up at the French Open.

No. 5 Stosur had an easier time of it with a 6-2, 6-3 victory over Italy's Sam Errani. The Aussie reached the French Open final in early June but followed with just seven wins in 12 matches heading into the final Slam of the season.

For the first time in the week, which has been characterized in weather terms by uncommon heat and humidity, rain caused a delay. Play was suspended for about 30 minutes in the afternoon.

As well, Hurricane Earl brought unpredictable winds into play.

But the conditions did not affect the Dementieva match, which was one of the first of the day.

"It was so strange, because since last evening we all were talking about how bad it's going to be today," Dementieva said. "Coming to the stadium, I was looking at the window, expecting, 'Where is the rain? Where is the wind?' You know, [we were] playing in absolutely perfect conditions this morning."

Teen Anastasia Pavlyuchenkova is on the way to the fourth round of a major for the first time in her career. The No. 20 seed from Russia beat Gisela Dulko of Argentina 6-1, 6-2.

Pavlyuchenkova, 19, beat current world No. 1 Caroline Wozniacki of Denmark when both were in the junior ranks.

Pavlyuchenkova will meet French Open winner Francesca Schiavone in the next round. The sixth-seeded Italian defeated No. 29 Alona Bondarenko of Ukraine 6-1, 7-5.

No. 16 Shahar Peer of Israel also moved on to the next round courtesy of a 6-4, 6-4 win over No. 19 Flavia Pennetta on Italy.

With files from Associated Press