Top seed Justine Henin-Hardenne slumped to a shock defeat in the second round of the French Open in Paris.
The Belgian lost 7-5 6-4 to Italian world number 86 Tathiana Garbin.
The world number one came into the tournament having not played for six weeks because of a virus and her lack of form and fitness told.
Henin-Hardenne became the first top seed to lose before the third round in the 79-year history of the women's singles at Roland Garros.
After the match Henin-Hardenne admitted she had returned from illness too soon.
"It was probably too soon to come back but I had to return one day," she said.
"I have no regrets over my decision - I just need more time to get back to 100%. I have come back in the past and I will do it again.
"She played really well today. It was a great day for her and a bad one for me.
"There are no excuses but now I will take a rest and start
practising again as Wimbledon is very much on my calendar. I will
see how I recover."
Garbin, whose highest ranking was 38 four years ago, was delighted to have her moment in the spotlight.
"I am just so happy. I really can't believe I have just beaten
the defending champion," the Italian said.
"But it was very tough because she is the world number one.
"My philosophy was to go on court and play easily. At the start she missed a lot and I got some easy balls. I was playing well and then I tried harder."
The Italian took the first set in 60 minutes breaking her opponent twice, as the Belgian's normally solid service fell apart, and broke again in the opening game of the second to go 2-0.
The fiesty Henin-Hardenne battled back to 4-2 before the brave Italian levelled to go 4-4 and then held serve for 5-4.
A Henin-Hardenne double fault set up two match points for Garbin but she squandered both with a long forehand and then a netted return.
But she carved out another match point and converted it into the biggest win of her career when she unleashed a blistering backhand pass which left Henin-Hardenne flat-footed.