The sporting world's most extraordinary sibling rivalry will be revived this weekend after Venus and Serena Williams [Images] won their third-round matches at the US Open on Friday.

The two American sisters will meet on home turf in the last 16 on Sunday after Serena beat Italian Francesca Schiavone 6-3, 6-4 and Venus won 6-3, 6-3 against Slovakia's Daniela Hantuchova [Images].

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Almost as intriguing a prospect will be the showdown between Russian top seed Maria Sharapova [Images] and emerging teenager Sania Mirza [Images], who on Friday became the first Indian woman to reach the fourth round at a grand Slam.

Men's favourite Roger Federer [Images] was at times tormented by a French box-of-tricks named Fabrice Santoro before moving through to round three with a 7-5, 7-5, 7-6 in a mini-classic.

Santoro, 32 and ranked 76, delighted the evening session Arthur Ashe Court crowd and drew smiles from the Swiss top seed by playing shots from between his legs, behind his back and even with eyes averted.

"I always enjoy playing against him," said Federer, who beat Santoro en route to winning the title last year. "He gave me a lesson the first time we played.

"He sizzled me up with his slice and spins. It was a pleasure to play against him."

Australian third seed Lleyton Hewitt [Images] eased through to the third round but Russian sixth seed Nikolay Davydenko and 1998 semi-finalist Carlos Moya [Images] of Spain suffered surprise losses.

Matches between Venus and Serena are intriguing -- often disappointing, always highly charged.

They last met at a Grand Slam in the 2003 Wimbledon final, when Serena won a subdued contest against an unfit Venus. Their overall head-to-head stands at 7-6 in Serena's favour but Venus won their last meeting in Miami [Images] in May.

FAVOURITE ON FORM

Only one of their 13 previous encounters -- their first meeting in the round of 64 at the 1998 Australian Open -- has come at an earlier stage in a tournament.

Wimbledon champion Venus, despite being seeded two places below Serena at number 10 and despite having lost five successive Grand Slam finals to her sister, is favourite on form, with Serena still looking tentative after knee and ankle problems.

"I think I'm playing okay," said Serena. "I definitely think I'm getting better and better. My knee's definitely feeling a lot better."

She described it as "extremely disappointing" to have to play Venus at such an early stage of a Grand Slam.

Venus, on the other hand, yelled at the Arthur Ashe Court crowd after beating Hantuchova: "Are you guys ready for the Williams sisters? We'll see you on Sunday."

Sharapova, who had dropped only three games in the first two rounds, beat German Julia Schruff 6-2, 6-4 to reach the fourth round.

Sharapova's preparations for the tournament were limited by a pectoral muscle injury, but she said: "I felt pretty good. I haven't had that many matches coming to the Open so it's good to get three matches in before the tough ones come.

"So far so good. When the tougher matches come I'm going to put more power into my shots."

Fellow 18-year-old Mirza knocked out France's [Images] Marion Bartoli 7-6, 6-4.

Mirza has a huge following among the one-billion-strong population of India and her match with Sharapova, herself a global tennis phenomenon, could be one of the highlights of the tournament.

"I just came here thinking I wanted to win one round and won three," said Mirza who is ranked 42. "I'm very happy about it."

They were joined by in-form Belgian fourth seed Kim Clijsters [Images], who was in unforgiving mood in her 6-1, 6-4 win over Japan's [Images] Ai Sugiyama.

She next faces battling Venezuelan Maria Vento-Kabchi, who earned a third consecutive three-set win, beating Israel's Shahar Peer 7-5, 4-6, 6-3.

Hewitt, the 2001 champion, showed great opportunism to defeat Argentina's Jose Acasuso 7-6, 7-6, 6-2. The Australian had to save a set point in the first set tiebreak against the world number 44.

He faces a third-round encounter with the thunderous serve American Taylor Dent, the imposing 25th seed whom he beat in the Wimbledon fourth round this year.

"I know what I'm going to get," said Hewitt. "It's never easy playing against Taylor, but he's going to give me a target and I've got to take my chances when I get them."

Unseeded Thai Paradorn Srichaphan [Images], ranked 51, upset Davydenko 6-4, 7-5, 6-3. He will next play Italian Davide Sanguinetti, who ousted 31st-seed Moya 3-6, 6-1, 6-2, 6-4.

Russian ninth seed Nadia Petrova recovered from a second set wobble to beat Laura Granville of the US 6-2, 7-5 and will face gifted Czech 16-year-old Nicole Vaidisova in the last 16.

British teenager Andy Murray ran out of steam in his second successive five-setter, beaten 6-0 in the fifth by France's Arnaud Clement.

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