One prematch glance yesterday at the data displayed on those fancy, new digital scoreboards at staid, old Wimbledon provided a pretty persuasive case for why Venus Williams might be considered the woman to beat.

The entry under career record at the grasscourt Grand Slam: "55-7." The listing of her best result: "WINNER 2007, 2005, 2001, 2000."

Yet another reason to like the American's chances: The way she served during the ensuing 6-4, 6-3 quarter-final victory over Tamarine Tanasugarn - smacking eight aces, saving nine of the 10 break points, tying her Wimbledon record with a 127mph delivery.

That extended Williams' winning streak at the All England Club to 12 matches, including 19 sets in a row. Nonetheless, at least one person who knows a thing or two about tennis and a thing or two about Venus Williams flatly rejected the notion that she's the favourite: Serena Williams.

Asked after her own impressive quarter-final victory - 6-4, 6-0 against 11th-ranked Agnieszka Radwanska - whether her older sister should be considered the likeliest champion, Serena shot back: "I would never sit here and say she's the favourite when I'm still in the draw. What are you on?"

Rather than a sibling rivalry, that response perhaps reflects nothing more than the sort of competitive drive that helped the younger Williams win eight Grand Slam singles titles. That haul includes the 2002 and 2003 Wimbledon championships, each time concluded by beating her sister.

One more win apiece, and they'll reprise the all-in-the-family final tradition Saturday. In tomorrow's semi-finals, Serena will face 133rd-ranked Zheng Jie, who became the first Chinese player to reach the semi-finals at a major tournament by upsetting 18th-seeded Nicole Vaidisova 6-2, 5-7, 6-1.

Venus next plays the highest-seeded remaining woman, No. 5 Elena Dementieva, who beat No. 21 Nadia Petrova 6-1, 6-7 (6), 6-3.

While Serena mixed in flat 120mph serves with spinning, kicking change-ups, Venus stuck with the hard stuff against Tanasugarn.

"I have a lot of power, so it helps," Venus said. "Definitely, the power helps."

She produced some of her best stuff when she needed to, particularly in the match's sixth game.

Tanasugarn earned six break points, and the first five vanished thanks to, in order, a 107mph service winner, a 102mph service winner, a 115mph service winner, a 94mph service winner and a 122mph ace.

"I'm really blessed to be able to have a serve to get me out of those issues," Venus said.

On break point No. 6, Tanasugarn managed to put her return in play but then slapped a forehand into the net.