Kirsten Flipkens almost quit tennis last year but was glad she stuck with it after beating former champion Petra Kvitova to reach the Wimbledon semi-finals.

Flipkens, who started the tournament as a 325-1 long shot for the title, beat 2011 champion Kvitova 4-6 6-3 6-4 under the Centre Court roof to set up a semi-final clash against France's Marion Bartoli tomorrow.

Rewind 14 months and the wide smile that stretched across Flipkens' face last night was nowhere to be seen.

Doctors discovered four blood clots in her calves because of a hitherto unknown genetic disorder. Flipkens was told that if she boarded a plane to Japan, where she was due to play in the Fed Cup, her legs would turn blue due to thrombosis.

After two months off court, Flipkens took a while to regain her form, but she looked like a potential champion yesterday when she came back from a set down to defeat Kvitova.

The Belgian summed up her turnaround in fortunes when she said: "Last year I didn't get into the qualifying of Wimbledon. I was ranked 262; today I'm a semi-finalist in a grand slam. It's more than a dream."

Flipkens still has to take blood-thinning tablets before she flies and must also wear rather unflattering compression socks in order to stop more clots forming.

But she thinks the setback, which came a few years after she was warned that her playing days could be over because of a back injury, helped her career, rather than hindered it, even though the injury meant she lost her funding from the Belgian tennis federation.

"Maybe I started to know what's important in life after that," said the 20th seed, who has won just one tour title in her career.

"I think winning or losing a tennis match doesn't make a big difference. I just started to see things in perspective.

"I've been through a lot of ups and downs throughout my career. I've had so many injuries. I was a world champion junior. The year after I had a really bad back injury. All doctors said my career would have been over normally.

"My love for the sport kept me going. I'm a person who doesn't like to break. I like to fight back."