In a women's match played yesterday, second-seeded Martina Navratilova staved off a set point in the second-set tie-break to beat Jenny Byrne of Australia, 6-4, 7-6 (9-7).
In other men's matches played yesterday, third-seeded Boris Becker, No. 9 Miloslav Mecir, No. 12 Mikael Pernfors and No. 14 Jonas B. Svensson all won, but 15th-seeded John Fitzgerald was beaten by Goran Ivanisevic, a Yugoslavian teenager, 6-3, 4-6, 6-3, 6-4.
In an early match today, Steffi Graf, the defending women's champion, barely missed registering a second straight shutout when she trounced Marianne Werdel of the United States, 6-0, 6-1, to move into the fourth round. Sixth- seeded Zina Garrison cruised into the fourth round with a 6-0, 6-0 victory over fellow American Kim Kessaris and No. 3 Gabriela Sabatini blanked Camille Benjamin.
Ivan Lendl, who can regain the No. 1 men's ranking by winning the title, moved into the third round by beating Carl-Uwe Steeb, a West German Davis Cup hero, 6-2, 3-6, 6-0, 6-3.
Seventh-seeded John McEnroe, complaining repeatedly about line calls, beat Broderick Dyke of Australia, 6-2, 4-6, 6-4, 6-3, in another second-round match.
Wilander said that his stay at the tennis summit has not exactly been a pleasant experience and that he was contemplating a break from the sport.
"Being No. 1 kind of got to me, because from there, you can only go down," he said. "I just don't enjoy playing right now. I can't seem to get motivated.
"Winning the U.S. Open was such a big thing for me. After that, nothing really seemed important."
Wilander beat Lendl for the U.S. title in September to become No. 1. A few weeks later, he lost a first-round match in Paris. That was followed by a third-round defeat in Stockholm, an early exit at the Masters in New York and a disheartening loss to Uwe-Steeb in the Davis Cup final.
Wilander's motivational problems were glaringly apparent against Krishnan, a smooth-stroking player whose father was a Wimbledon semifinalist in 1960 and 1961.
Krishnan baffled Wilander with his arsenal of off-speed shots, forcing him into a series of uncharacteristic errors.
"It's the biggest win of my career," said Krishnan, who won a tournament in New Zealand last week. "To beat the No. 1 player in the world is very thrilling."
Krishnan, 27, squandered three match points before sealing the victory with a backhand volley.
"You feel the pressure in a situation like that," he said. "The court seemed to get smaller."
Wilander, who had won three of the last five Australian Opens, was disgusted with his performance.
"I played terribly," he said. "Mentally, I wasn't into the match."
Wilander said he might stop playing for a while if his attitude did not improve.
"I will just have to see what happens in the next few days," he said. ''If I still feel this way, I may take some time off."
Krishnan's racket broke as he was hitting his first serve on the ninth point of the third-set tie-breaker, when he was leading by 5-4. Krishnan faulted on the next serve.
The Indian reached his fourth match point when Wilander mis-hit a forehand to go down by 5-6. Wilander served, and after a brief exchange, Krishnan moved into the net and hit a backhand volley for the winner that completed the upset.
In other women's matches yesterday, fourth-seeded Pam Shriver, No. 5 Helena Sukova, No. 10 Mary Joe Fernandez and No. 15 Hana Mandlikova advanced to the third round.