MELBOURNE, Australia -- Former Wimbledon champion Michael Stich was knocked out of the Australian Open by Karel Novacek of the Czech Republic in the third round Friday while Pete Sampras moved ruthlessly into the final 16, putting aside concerns about the health of his coach Tim Gullikson.


Stich had surged through his first two matches at the Open, winning both in straight sets and dropping only 14 games in the process -- but was stopped in his tracks by Karel Novacek, 29, and flew straight home to Germany after the loss.


The unseeded Czech, a semifinal loser to Stich at last year's U.S. Open, outplayed the lackluster No.7 seed 7-5, 6-2, 6-4 in just under 100 minutes.


After searing heat made conditions uncomfortable for players on Thursday, rain fell Friday morning, preventing play on outside courts for more than two hours. Play continued on center court under the retractable roof.


Stich was unhappy to find himself playing indoors.


"The conditions change 100 percent. It is a totally different ball game," he said. "It was an advantage for him to play indoors. It is supposed to be an outdoor tournament and that is what it should be."


Sampras, the defending champion and No.1 seed, outclassed Swede Lars Jonsson 6-1, 6-2, 6-4, steamrolling through the first two sets before Jonsson offered some resistance in the third.


Gullikson, who suffered two minor strokes in the past three months, was hospitalized after suffering a dizzy spell an hour before Sampras' match.


"I just had to block it out and not worry about it and concentrate on my tennis," Sampras said. "I realize he's in good hands. It's always nice to have that support, but when it's not there, I've been around long enough to handle it."


It was Sampras' third successive straight-sets victory. He thrust his arms in the air in triumph and then threw his towel into the crowd. He was satisfied with his performance, which included 13 aces and next plays No.15 seed Magnus Larsson, the Grand Slam Cup winner. Larsson had a walkover when fellow Swede Thomas Enqvist withdrew with a fever.


Jim Courier, the No.9 seed and a two-time champion, scored a predictable 6-3, 6-3, 6-3 victory over Australian left-hander Mark Woodforde in the evening session.


No.5 seed Michael Chang, of the U.S. and No.13 Andrei Medvedev, of Ukraine, also advanced to the last 16.


Chang, who has not previously made it past the third round in Melbourne, defeated powerful Czech player Martin Damm 6-3, 7-5, 6-3 in difficult windy conditions on Court 2.


The American, who has been working on his serve, had 14 aces and made only 15 unforced errors in a confident display. Chang now meets Olivier Delaitre, a 6-4, 6-4, 6-2 winner over Russia's Andre Olhovskiy.


Medvedev cruised past Stefano Pescosolido of Italy 6-4, 6-3, 6-3, serving nine aces and hitting 33 winners to his opponent's 19.


There was also an upset in the women's singles with Kyoko Nagatsuka, 20, of Japan, who never has made it past the second round of any Grand Slam, ousting No.14 seed Amy Frazier, of the U.S. 6-3, 6-3.


Spain's Conchita Martinez, the reigning Wimbledon champion and No.2 seed, also advanced to the fourth round with a 6-3, 2-6, 6-3 win over power-server Kristie Boogert of the Netherlands. Martinez was troubled by a neck injury during the match and used ice on the injury during changeovers. "It is not perfect, but it is getting better all the time," she said.


Martinez now will face unseeded Irina Spirlea of Romania, who defeating Japan's Yone Kamio 2-6, 6-3, 6-3.


France's Mary Pierce, the No.4 seed, was frustrated by Dally Randriantefy, 17, of Madagascar before winning 6-3, 6-3. She now plays No.10 Anke Huber of Germany, a 6-0, 6-1 winner over Indonesian Yayuk Basuki.


No.6 seed Lindsay Davenport of the U.S. downed Sandrine Testud of France 6-3, 6-4 and now plays No.12 Brenda Schultz.