A sceptical Capriati said Serena appeared on top of her game until things began to go against her.

Indeed Capriati claimed the younger Williams sister managed to develop some kind of health problem every time they met.

"I had no idea until she took a bathroom break there was anything wrong with her.

"But I am used to it as everytime we play there is something going on."

But not the kind of player to let a spot of gamesmanship get to her, Capriati was unfazed.

"She usually takes her time before I serve but I think that she's just a slow player. She does it in every match, not just against me."

After the defeat Serena claimed she had been suffering a "gastro viral infection" which had left her unable to eat and without energy.

The number five seed said she had been on the verge of pulling out of her match against Magdaleena Maleeva on Friday but decided to carry on.

Though she took the first set - on a tie break - Serena never seemed at ease with herself.

During the early stages of the match her ground strokes were uncontrollably wild.

During rest-breaks she clutched the pre-match notes she often makes, as if scrutinising them for the answer to her predicament.

While Capriati appeared to have her measure in the baseline slugging stakes, Serean appeared to resort to mind games.

After breaking Capriati's serve to take a 3-2 lead in the second set, she asked for a halt in play because she was suffering light-headedness.

Mental toughness

Four bananas were brought out on court.

In the meantime, Capriati shrewdly called the trainer to help her stretch and stay loose, leaving the court for three minutes for her buttock muscle to be rubbed.

When play resumed, Williams raced to a 5-3 lead and at 30-love up was two points away from victory.

Instead, Capriati played two fantastic returns to set up another break, one of 13 in the match, and spark a spectacular Williams collapse.

She lost the next nine straight games, after the eighth dashing from the court in panic claiming she "couldn't hold it anymore".

She could have equally been talking about her stomach or her mind.

Whistling back

The only doubt in Capriati's mind was whether it was her own mental or physical toughness that put paid to Serena.

"It was probably a bit of both - a bit of experience and the consistency I showed on the big points."

While this match was just another great twist in the Capriati comeback story, it is one that leaves questions to be asked about Serena's mental toughness and desire to win.

She raced through her opening matches, losing fewer games than any other player, yet seemed to lack the edge to make the step up.

She looked genuinely perplexed to see some of her 115mph serves come whistling back at her.

Then when the going got tough and Capriati ran out fighting, Serena ran to the bathroom.