Title is not an obsession for me, says Rafa Nadal

The US Open is the only grand slam title missing from Rafa Nadal's CV, yet the world No.1 is surprisingly not obsessed about winning in New York and joining an illustrious group of tennis greats.

"Seriously, for me, to complete the grand slam at this moment is not a goal," the 24-year-old Spaniard said after his 6-2, 7-6 (7/5), 7-5 second round victory over unseeded Denis Istomin of Uzbekistan.

"For me, the goal is to try to improve my level, to play well (in] the next match, and we will see what happens next Sunday. For me it is not an obsession."

Nadal, winner of the French Open five times, Wimbledon twice and the Australian Open once, has come to Flushing Meadows armed with a faster serve and an improved volley that could push him past the semi-finals, where his past two US Open campaigns have ended.

Nadal did not drop serve on Friday, producing eight aces and clocking a fastest delivery of 134mph. The Spaniard also won 13 of 19 points at the net and will be confident of victory against unseeded Frenchman Gilles Simon in the third round.

"For the moment, it's working really well," he said about his serve. "So I'm going to try to keep playing like this. Serving like this is a big confidence in my game."

Nadal, who is aiming to join the illustrious group of Roger Federer, Andre Agassi, Roy Emerson, Fred Perry, Rod Laver and Don Budge and win all four major titles, said an adjustment made just before the Open had made the difference in his service delivery.

"I changed a little bit the grip, like five or six days ago," the Mallorcan said. "So I tried to play the serve a little bit more aggressive."

Defending women's champion Kim Clijsters will face former world No.1 Ana Ivanovic in the fourth round of the US Open after easy wins were the order of day five at Flushing Meadows.

Clijsters won 12 games in a row to beat Wimbledon semi-finalist Petra Kvitova 6-3 6-0, while Ivanovic dropped just two more games in beating France's Virginie Razzano 7-5 6-0.

And third seed Venus Williams continued the theme in the evening session with a 6-2 6-1 win over qualifier Mandy Minella from Luxembourg to set up a last-16 clash with Israel's Shahar Peer.

Kvitova, who lost in the first round of her next five tournaments after her last-four defeat to Serena Williams at the All England Club, raced into a 3-0 lead against Clijsters with two breaks of serve.

That meant the Czech left-hander had already won more games than during her previous meeting with Clijsters - a 6-1 6-1 defeat in Miami this year - but that was as good as it got for the 27th seed.

Ivanovic has dropped to 40th in the world rankings due to injuries and a loss of form, but has lost just 13 games in her first three rounds in New York.

Williams, playing her first tournament since Wimbledon after a knee injury, looked set for a tougher time against world No.185 Minella when the first four games all saw breaks of serve.But the two-time champion, watched by sister Serena who is out with a foot injury, then won ten of the next 11 games to book her place in the fourth round.