CALGARY, FEB. 9 -- This was supposed to be Nicky Thometz's big week as he prepared to chase Olympic gold for the United States Sunday night.

But with five days left to train, the world-record holder in men's 500-meter speed skating is scratching to regain lost strength as he recuperates hurriedly from a blood disorder. At the moment, the weakened former gold-medal favorite isn't even favored to finish first on his own team.

"It'll be interesting to see how Nicky does," said Eric Heiden, who won five golds in the 1980 Olympics at Lake Placid. "It's important to come into a competition like this with a lot of confidence. He may have hurt himself psychologically with his performance in Milwaukee."

At the World Sprint Championships last weekend in Wisconsin, Thometz was fourth at 500 meters and ninth overall, far behind teammates Dan Jansen and Eric Flaim. Heiden now rates Jansen the top U.S. 500-meter prospect.

Initially, Thometz denied his poor performance was due to weakness from a long bout of illness, first with the flu and then with mysterious low blood platelet counts that put him in the hospital in December.

But today, after practice on the smooth indoor ice at the Olympic oval here, he conceded he's in an uphill fight. "I'm not where I wanted to be at this point," he said. "I'm having a little trouble recovering. I'm skating well technically but I've lost power and strength."

The hardest part "is staying up mentally," said Thometz, a 24-year-old veteran of the 1984 Olympics, where he was fourth in the 1,000 meters. "But I'm getting better all the time."

Thometz's troubles are trouble indeed for the U.S. speed skating team, which is expected to be one of the nation's top medal-winners over the next three weeks.

His 36.55-second world record was set in Heerenveen, Holland, at an indoor rink much like the one here. At 5 feet 9, 165 pounds, and with a smooth, technical skating style, Thometz is tailor-made for indoor skating, where there is less of a premium on size and power to overcome wind, rough ice and other outdoor problems.

Technically, Thometz is still skating well, according to teammate and women's 500-meter favorite Bonnie Blair, "but he's got problems. He told me he just doesn't have what he had.

"But that doesn't mean he can't get it back," said Blair. "We're all going for a peak, and Nick's capable of getting to that peak again."

Should Thometz falter, Jansen is primed to take his place. The 23-year-old Wisconsinite won the 500 at last weekend's sprints and even before Thometz's problems was considered a tough rival, though not custom-made for the Calgary Oval.

Asked today to rate Jansen's chances, Heiden at first picked him to take the 500-meter gold Sunday night over Japan's Akira Kuroiwa, then retrenched a bit.

"I don't know that Dan can win," he said. "He may be a little bit too strong and heavy."

At 6 feet, 185 pounds, Jansen, who was fourth in the 1984 Olympics at 500 meters, may have problems with Calgary's tight, fast turns.

Jansen, who nearly fell in a corner in competition here last fall, recognizes the problem and for two weeks before the world championships was practicing here, working on controlling his corners. "The track probably favors less-powerful skaters," he said today, "but I consider myself a power skater and I feel real good right now."

Thometz and Jansen were expected to produce three or four medals in the shorter distances of 500, 1,000 and 1,500 meters, with the first test coming early in Sunday's televised 500 meters.

Americans must wait a bit longer to see the U.S. women's superstar, Blair, who won the 500-meter championship at Milwaukee over East German archrival Christa Rothenburg in bitter, windy conditions.

The result left Blair glowing today as she prepared for her Olympic 500-meter test Feb. 22.

"It went well," she said. "Conditions weren't great but I skated real well. We were paired together and one-third of the way into the last turn, I realized I had her. So I feel really confident here in Calgary."

Blair also is expected to win a medal at 1,000 meters, where the going will be rougher against East German Karin Kania, who was first at the distance at Milwaukee. Blair was fourth.