Martina Hingis has taken another step towards tournament victory at the Masters Series in Key Biscayne by defeating Spain's Magui Serna in the fourth round.

The Swiss player and world number one needed 76 minutes to defeat Serna, currently ranked 27th in the world, in straight sets, 6-3, 6-4.

The match did not start well for Hingis, as Serna broke her serve and went on to take an initial 3-1 lead in the first set. But Hingis quickly regained form taking all of the remaining games in the set and outclassing her opponent in a hard-fought second set.

"It was tough," said Hingis after the match. "She plays her forehand with a lot of topspin, which means I had to do a lot of running around."

"Magui played her game well," Hingis continued, "and the match was tiring for both of us because of the heat."

Hingis puts her recent tournament success down to the fact that she has abandoned doubles matches to concentrate on her singles game: "I now have time to do some other exercise every day, like jogging or rollerblading. This gives me time to switch off from the game and recharge my batteries."

Hingis now faces Germany's Anke Huber in the quarter finals, and the record books are in favour of a Swiss victory: Hingis has won 11 of her previous 12 encounters with Huber.

Asked about her chances of beating Huber to win a place in the semi-finals, Hingis seemed confident: "If I play the game I know I can, I have a good chance."

In men's tennis, Hingis's compatriot, Roger Federer, added to his recent successes by knocking out the Australian, Mark Philippoussis, at the same tournament.

Twenty-fourth ranked Federer staged an upset by beating the 16th seeded Philippoussis 3-6, 7-6 (7-4), 6-2.

Federer, who won his first career title last month in Milan, was able to break his opponent twice in the final set, in the first and seventh games, to advance to the fourth round.

"It could have gone either way," Federer said. "I'm happy with the way I fought today and at the end, I came up with great shots."

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