Nadal marches on in Miami

Rafael Nadal comes from behind in both sets to beat Stanislas Wawrinka to reach the quarter-finals in pursuit of his first Sony Ericsson Open title.

The world No 1 Rafael Nadal advances to the quarter-finals of the Sony Ericsson Open with a straight sets victory over Stanislas Wawrinka.

KEY BISCAYNE, FORIDA // Rafael Nadal came from behind in both sets to beat Stanislas Wawrinka of Switzerland 7-6 (2), 7-6 (4) on Tuesday to reach the quarter-finals in pursuit of his first Sony Ericsson Open title. The top-ranked Nadal won despite converting only one of 12 break point chances. He had four match points at 5-4 in the second set, but the No 16 seed Wawrinka hit a succession of big serves to stay alive.

"Sure I can play better," Nadal said, "but I'm happy with my match. It's an important win for me." The two gruelling sets lasted two hours, 42 minutes before Nadal closed out the victory with a backhand cross court passing shot at 1220am local time. "The best players are winning always, no?" Nadal said. "Winning titles is almost more difficult than ever, because you have to play against the best."

His opponent in the quarter-finals tomorrow will be sixth-seeded Juan Martin del Potro of Argentina. The second seed Roger Federer overcame eight break points in a remarkable sequence to take the lead for good as he beat the American Taylor Dent 6-3, 6-2. Federer will meet another American, Andy Roddick, in the quarter-finals today. Dent's only breakpoint chances against Federer came in their 26-point fifth game.

Federer double-faulted twice in the game and hit several hurried shots into the net, which had him mumbling, then screaming. "I had to save so many break points over and over again," Federer said. "I was serving against the wind, so I was struggling with my first serve there a bit. He did well to keep coming at me and creating opportunities. It was definitely a big game for me." Federer finally hit a service winner to hold, and his game improved after that.

Dent played serve-and-volley and also charged the net behind some returns, but he won barely half his points at the net. "I like playing against that kind of style," Federer said. "When I came on tour, this is how many guys were playing, even myself - coming to the net, forcing the issue, keeping the points short." Roddick, seeded fifth, also left the baseline behind as he beat the Frenchman Gael Monfils 7-6 (2), 6-4.

Roddick won 22 points at the net, showing a willingness to move forward, highlighting his more well-rounded game under his new coach Larry Stefanki. While Roddick has improved his volley and backhand in recent months, he still possesses an overpowering serve and won 38 of 44 first-serve points against the No 9 seed Monfils. Roddick leads the ATP Tour in victories this year with a record of 26-4.

"I feel good and I feel confident," he said. "I think the big difference is you get to those 30-all points, and I just feel calm and like I'm going to play my point the way I want to. I have maybe some more options now." Other men's fourth round winners were Novak Djokovic of Serbia, the third seed, fourth-seeded Andy Murray of Britain, Del Potro, Fernando Verdasco and Jo-Wilfried Tsonga of France.

Djokovic will play Tsonga in the first men's quarter-final today. Nadal will face del Potro tomorrow and Murray will play Verdasco. Roddick's most recent match against Federer came in the Australian Open semi-final in January. Federer won in straight sets. "The thing that Roger seems to do really well against me is serve really well," Roddick said. "Obviously it'll be tough. But I'm going to go out there and just go after it."

In other men's fourth round matches, Djokovic beat No 21 Tomas Berdych 6-3, 6-2. Murray routed Viktor Troicki 6-1, 6-0. Tsonga won 6-7 (4), 6-3, 6-2 against Gilles Simon, the highest-seeded man to be eliminated. Del Potro beat the No 11 David Ferrer of Spain 6-3, 6-2, and Verdasco defeated the Czech Radek Stepanek 6-2, 6-2. Eighth-seeded Svetlana Kuznetsova of Russia outlasted 18-year-old Dane Caroline Wozniacki in the first women's quarter-final, 6-4, 6-7 (5), 6-1.

When the two hour, 54-minute match in humid conditions ended, Kuznetsova slowly crumpled to the court in exhaustion and relief. The 2006 champion will play in the semi-finals tomorrow against the 11th seed Victoria Azarenka of Belarus, who beat the unseeded Australian Samantha Stosur 6-1, 6-0. *AP