Serena Williams after her win at the Flushing Meadows on Sunday

New York: Former champion Serena Williams stepped up her game to beat Wimbledon runner-up Marion Bartoli 6-3, 6-4 to reach the quarter finals of the US Open on Sunday.

Second seed Rafael Nadal continued to overcome knee problems when he outclassed Frenchman Jo-Wilfried Tsonga 7-6, 6-2, 6-1 to reach the fourth round.

Also into fourth round were David Ferrer of Spain and Juan Ignacio Chela of Argentina. Ferrer beat Nalbandian 6-3, 3-6, 4-6, 7-6 (5), 7-5 while Chela got the better of Ljubicic 6-4, 6-7(5), 2-6, 6-3, 6-3.

The No. 8-seeded Serena was much stronger and faster than Bartoli, and fittingly finished off the Frenchwoman with back-to-back aces.

Serena also had no problems with the chair umpire. In her last match, the two-time Open champion got reprimanded for reading from her pink notebook during the match.

Even though she is an eight-time major champion, there were doubts about her going into the final Slam of the season. She hurt her left thumb at Wimbledon and had not played since then, prompting some to wonder how effective she’d be in this tournament.

Instead, she’s so far put on a repeat performance from the Australia Open. Hurt for much of 2006, she went into Melbourne unseeded, then reeled off a strong run to win it. Serena would play the winner of the match between No.1 Justine Henin and No. 15 Dinara Safina. If it’s Henin, it would be their third consecutive major quarter final meeting. Bartoli had a breakthrough at Wimbledon, finishing as the runner-up to Venus, but has struggled to duplicate that success.

Using a two-handed grip from both sides, Bartoli is known for her unusual training methods — her father likes to hit multicoloured, multi-sized balls at her during practice to sharpen her focus.

Serena, however, hit the same kind of ball at Bartoli all match. As in, really hard.

She held a 32-10 edge in winners and her fastest serve was 124mph to Bartoli’s 106. Serena also stayed in control, putting 81 per cent of her first serves in play.

Fifth-seeded Andy Roddick breezed, beating 2002 Australia Open champion Thomas Johansson of Sweden 6-3, 6-2, 6-0 to reach the fourth round.

“I’ve got to try to find myself a hot date later,” said Roddick, who’s dated actress Mandy Moore and been linked to Sharapova in the past, “so I tried to get off the court a little faster.”

In other men’s matches, No. 4 Nikolay Davydenko of Russia beat No. 28 Nicolas Almagro of Spain 7-5, 6-0, 7-5, No. 6 James Blake beat Stefan Koubek 6-4, 3-6, 7-6 (5), 6-1 in a match that finished after 1 a.m. local time Sunday, while No. 9 Tomas Berdych of the Czech Republic and No. 10 Tommy Haas of Germany advanced.

One minor upset came when No. 19 Briton Andy Murray lost to 43rd-ranked Lee Hyung-taik of South Korea 6-3, 6-3, 2-6, 7-5.

Lee, in the U.S. Open’s fourth round for the first time since 2000, will meet Davydenko.

       (AGENCIES)