Zheng grabs limelight in Williams show

Chinese wildcard Zheng Jie provided an absorbing sub-plot to Williams sisters domination on quarter-final day at Wimbledon yesterday.

Zheng beat Czech Nicole Vaidisova 6-2 5-7 6-1 to become the first Chinese player to reach a grand slam singles semi-final and the first woman to go so far at Wimbledon after requiring a special invitation from the All England Club.

During an unpredictable tournament riddled with shocks the one constant has been the ruthless efficiency of Venus and Serena Williams and now they look odds on to contest their third Wimbledon final on Saturday.

Venus, champion at Wimbledon four times and twice runner-up to her younger sister, was engaged longer than expected in beating Thai surprise Tamarine Tanasugarn 6-4 6-3 before Serena made mincemeat of Poland's Agnieszka Radwanska 6-4 6-0.

Serena will play Zheng in the semi-finals while Venus must get past fifth seed Elena Dementieva after she survived a mid-match wobble to beat fellow Russian Nadia Petrova 6-1 6-7 6-3 and reach Wimbledon's last four for the first time.

"I was so tight, I was so close to finishing it in two sets and I don't know what happened," Dementieva, who lost to Dinara Safina in the quarter-finals at Roland Garros this year after having a match point, told reporters.

"I suddenly started to think about the French Open quarter-finals and it was difficult (to get that out of my head). It was so exhausting."

Dementieva threw away a 5-1 lead in the second set but instead of capitulating as she did against Safina she managed to steady her nerves and regain control.

Despite being the highest seed to skip past the banana skins that have caught many of the top players, Dementieva will start as underdog against seventh seed and defending champion Venus.

The American, who like her sister has not dropped a set at this year's championships, was not at her best against Tamarine but had plenty in reserve when it was required.

Tamarine, at 31 the oldest player to reach the last 16, played admirably despite being outgunned by Venus and had she taken one or two more of the numerous break points her patient baseline game provided, another shock might have been possible.

"I expect when times are tough to get going, those break points you just have to play better and I'm really blessed to have a serve that gets me out of those issues," Venus told reporters, playing down a late scare when she appeared to pull up sharply after a slide.

"I'm fine. I mean, I'm walking around on two legs, doing good, so I'm not really concerned right now."

Zheng, who repaid the organisers' gift of a wildcard by knocking world number one Ana Ivanovic in round three, claimed her fourth seed of the championships with a calm and controlled defeat of Vaidisova.

She appeared to be tiring in the second set as Vaidisova became more aggressive but she was the more resilient player in the decider and raced to victory.

Zheng, who missed the 2007 season with an ankle injury, turns 25 on women's finals day but with Serena Williams in a mean mood she is unlikely to be celebrating it on Centre Court.

The sixth seed was too powerful, too consistent and too fired-up as she continued to torment the Radwanska family.

In the second round she beat Urszula Radwanska, Agnieszka's younger sister, while in the doubles she and Venus beat Agnieszka and her partner Marta Domachowska.