KEY BISCAYNE, Fla. (AP) -- Serena Williams advanced to another sibling showdown against her sister by beating Martina Hingis 6-4, 6-0 Wednesday in the quarterfinals at the Nasdaq-100 Open.

Williams' opponent in the semifinals Thursday will be No. 2-seeded Venus Williams, who notched her 22nd consecutive victory at Key Biscayne on Tuesday, beating Elena Dementieva 5-7, 6-3, 6-2.

Venus, the older sister by 15 months, has won five of the six previous matches against Serena. They'll meet for the first time since Venus beat Serena in last year's U.S. Open final.

``Tomorrow should be a great match,'' Serena said. ``I'm looking forward to playing well, and I'm sure Venus is too.''

Serena, seeded eighth, overpowered the No. 3-seeded Hingis to take a 7-6 edge in their rivalry. Williams won the final seven games, losing only two points during one four-game stretch.

In men's play, top-seeded Lleyton Hewitt needed only 10 minutes to finish a rain-interrupted victory over American James Blake, 6-4, 6-1.

Hewitt led 3-1 in the second set Tuesday when the match was suspended. He broke Blake's serve six times, including twice Wednesday to complete the fourth-round victory.

Hewitt, seeking his third title this month, extended his winning streak to 14 matches. He earlier won at Scottsdale and Indian Wells and has won 21 consecutive matches on U.S. hardcourts dating back to his title run at the U.S. Open last year.

The Australian's opponent in the quarterfinals Thursday will be the winner of Wednesday's match between No. 6-seeded Marat Safin and qualifier Fernando Gonzalez, who upset Pete Sampras in the third round.

On Tuesday, No. 9-seeded Andre Agassi moved one win closer to his fifth Key Biscayne title and second in a row, beating No. 8 Thomas Johansson 7-5, 6-2.

A wrist injury kept Agassi from bidding for his third consecutive Australian Open championship in January, and Johansson won in his absence. Agassi is now 4-0 against the Swede and 12-2 since returning from his injury.

``It was definitely a letdown not playing Australia this year,'' Agassi said. ``It's been a great place for me to get my year started. But now I've got a lot of energy, and I'm coming out of my shoes looking for competition.''

Two men's fourth-round matches ended with injuries Tuesday. No. 5 Tim Henman retired because of a stiff neck trailing No. 12 Roger Federer 6-2. Gaston Gaudio quit with severe cramping while trailing Juan Ignacio Chela 6-1, 5-7, 4-3.

Henman hurt his neck when he collided with a stranger going through a doorway Monday.

``I can't really look up,'' Henman said. ``So that rules out serving.''

Chela's quarterfinal opponent will be 1998 champion Marcelo Rios, who beat No. 16 Alex Corretja 6-2, 6-2. No. 20 Nicolas Lapentti edged Adrian Voinea 6-2, 3-6, 6-3.

The weather was sweltering when the second-seeded Williams and No. 12 Dementieva took the court. Williams won despite blowing a 3-0 lead in the first set and committing 48 unforced errors and 10 double-faults.

``I never really felt that I was going to lose,'' she said. ``Theoretically, I should have won the first set.''

Williams was surprised to learn she lost her serve four times and broke serve six times.

``My word,'' she exclaimed. ``I didn't know it was that crazy out there.''

The shot of the day -- and perhaps the tournament -- belonged to Agassi. In the opening game of the second set, he chased down a Johansson volley to angle a running forehand crosscourt for a winner.

``That was a beauty,'' Agassi acknowledged. ``Sometimes those shots happen.''

Two matches were scheduled for Wednesday night -- Chela against Rios, and No. 4 Kim Clijsters against No. 5 Monica Seles in the last women's quarterfinal.