She beat 18th seed Nicole Vaidisova 6-2 5-7 6-1. The match was a showcase for her attacking style and her tenacity. In the first set, she exploited Vaidisova's only double-faults to break her serve twice, and defended four break points of her own. Vaidisova claimed the second set, but once Zheng broke to go 3-1 up in the third set, she did not look back.

This is the latest triumph in what is turning out to be a dazzling tournament for the 24-year-old. Zheng won the 2006 Wimbledon doubles competition with Zi Yan, but an ankle injury stopped her from playing for the whole of 2007. Her ranking drifted to 133 but she entered Wimbledon this year on a wild card.

Then she astonished the crowd on day five by beating top seed Ana Ivanovic in two sets. “She has very powerful shot. She stays very low, so the balls are coming much faster through the air” Ivanovic said after the match.

Zheng went on to despatch Hungarian Agnes Szavay in round four and now Vaidisova.

“Did I think I could reach the semi-finals when I was given a wild card? No.” Zheng said. “I cannot believe I have got this far.”

So there is now a chance she will play in the final, which happens to be on her birthday. But before that can happen, she’ll have to overcome Serena Williams. Williams is on blistering form this year, thrashing Agnieszka Radwanska in the quarter finals 6-4 6-0.

“Serena is a two-times winner and a very prominent player on grass - I am in the semi-finals for the first time” Zheng said. “In 2004, I lost to her in the first round when she was the defending champion. I hope I do better this time.”

Zheng, who is from Chengdu, has pledged to give her share of any winnings to victims of the earthquake in Sichuan. But even if she makes her exit before the final, she has done much to raise the profile of Chinese tennis, impressing enormously the players, pundits and crowds of Wimbledon.

Her success has also raised Wimbledon’s profile. Former women’s No 1 Tracy Austin made a prediction: “There are going to be more people watching that semi-final than I think ever in the history of Wimbledon.”