Kirsten Flipkens came from a set down to beat former champion Petra Kvitova in their Wimbledon quarter-final.
Flipkens, the 20th seed, prevailed 4-6 6-3 6-4 in two hours and five minutes under the Centre Court roof and will take on Marion Bartoli in the last four.
Kvitova, the only major winner left in the draw, was feeling unwell throughout but appeared in control after breaking twice on the way to taking the opening set.
But the Czech left-hander's performance deteriorated and she needed a visit from the doctor to check her temperature at 5-2 down in the second set.
The eighth seed did manage to hold in the next game but Flipkens stood firm to serve out the second set and extend the contest into a decider.
And the Belgian, playing in her maiden Grand Slam quarter-final at the age of 27, made her move by breaking for a 5-4 lead in the third set before completing victory with an ace on her third match point.
"It's amazing, more than a dream come true to be in the semi-finals of a Grand Slam, it's ridiculous," said Flipkens, who won the girls' Wimbledon title 10 years ago.
"Last year I did not even get into the qualifying at Wimbledon. I was 260th in the world and today I am in the semi-finals of Wimbledon. It cannot be better.
"I still cannot believe it. I was so calm, I had nothing to lose, I just went for my shots.
"Petra was playing really well in the first set and I really had a lot of problems with the way she was playing and I just had to go for it from the second set on. I am so happy. You can't imagine."
Flipkens had to put away her rackets for a while last year when she was diagnosed with four blood clots in her calf.
She lost her funding from the Belgian tennis federation and she ended up travelling to tournaments without a coach or physio.
Kim Clijsters stepped in to help her compatriot get back on her feet and Flipkens paid tribute to the four-time major winner.
"Kim was one of the few who believed in me," Flipkens said. "I can count on one hand how many people still believed in me and she and my sponsors are included in that."