The 16-year-old Russian was defeated by Jana Novotna, 6-7, 6-3, 6-3, in a match delayed overnight with the Czech No 3 seed leading 4-2 in the final set. Novotna required only 14 minutes to complete a victory which took her into a quarter-final meeting with Monica Seles today.
For Kournikova, that was the least of the story. She still could not understand why she had been refused permission to go to the bathroom after making an unsuccessful appeal against bad light during a changeover at 1-4 the night before.
"It was the first time ever in a match that I had to go to the bathroom, so it was something very new for me," Kournikova said. "In the rule book you can see that a player has a right to take a bathroom break twice. It doesn't matter if it's in the middle of the point. Even when you come on the court and start warming up, you can go to the bathroom. It doesn't matter if it's after one minute or two hours. We played an hour and 40- something minutes.''
The International Tennis Federation's rules state that, "A bathroom break may be taken when necessary, but preferably at the end of a game or on a changeover. The break may not exceed five minutes, except when taken on a changeover, in which case the player receives an additional 90 seconds.''
A spokesman for the Women's Tennis Association Tour said the rule depended on the referee's interpretation of "necessary", and in this case the referee did not consider it was necessary for Kournikova to go to the bathrooom. "The request was denied as the change of ends was almost over. Tournament officials felt the toilet break should have been requested at the beginning of the change of ends."
Asked during her press conference if she really needed to go to the bathroom or was trying to stall until the light got darker, Kournikova said, "No. Like I said, it was the first time ever I had to go to the bathroom. I think I have a right to go the bathroom. It doesn't matter what I was doing.''
Novotna took a pragmatic view. "If the rules are there and you know how to use them, why not?" she said. "You have to do everything you can to win the match. If you can use the rules at the right time, that's the way tennis now is.''
Kournikova, visibly upset, was able to win her service game for 2-4, at which point Novotna successfully appealed against the light. The decision was taken by the assistant referee, Bruno Rebeuh, the official who famously came into conflict with Jeff Tarango and his wife, Benedicte, while umpiring at Wimbledon in 1995.
Although John Frame, of Britain, umpired the Novotna-Kournikova match, Rebeuh was at the courtside. Another fourth round match, between Iva Majoli, the holder, and Conchita Martinez, had already been halted at one set all (Majoli won yesterday, 7-6, 6-7, 6-3).
"I think the match with Majoli and Martinez was called off nearly an hour before out match finished," Kournikova said. "We finished at 9.28. It was pretty dark, but they said it was darker over there, a hundred yards away.''
Asked if she had visited the bathroom after her match, Kournikova said, "No, I was holding it until today. Now, every time I go to the bathroom, I should ask the WTA, 'Can I go to the bathroom, please?'''
Kournikova spent part of her afternoon sitting beside the great Brazilian footballer Ronaldo watching her Russian compatriot Marat Safin play Cedric Pioline, last year's runner-up at Wimbledon. Pioline started a French frenzy of delight by winning, 7-5, 4-6, 6-7, 6-4, 6-4. He will now play Hicham Arazi, of Morocco.
Arazi advanced with 6-2, 6-4, 3-6, 6-3 win against Spain's Alberto Berasategui. Filip Dewulf, of Belgium, a semi-finalist last year, beat Spain's Francisco Clavet, 7-5, 6-3, 6-1while Alex Corretja, the No 14 seed, defeated Australia's Jason Stoltenberg, 6-4, 6-4, 6-3.