COPENHAGEN, Denmark -- Mike Tyson insists he's in the best shape since he got out of prison and returned to boxing six years ago.

"Most of the problems since I came out of prison have been I've just never been in condition," Tyson said Wednesday, toweling beads of sweat from his shaved head at a Copenhagen gym.

"I've been beating these guys with brute strength and a lot of intimidation. But I've never been in condition."

That could be bad news for Denmark's favorite son Brian Nielsen (62-1, 43 KOs), who faces Tyson (48-3, 2 no contests, 42 KOs) Saturday in a 10-rounder in the Danish capital.

Out of the ring for a year, the former undisputed heavyweight champion is beefed up and his upper body is even more sculpted. He showed his explosive power Wednesday, repeatedly lifting sparring partner Stacy McKinley's feet off the canvas with thumping body combinations.

"I feel in great condition now and I just feel a whole lot different," said Tyson, who has been working with conditioning coach Gunnar Peterson for four months.

"I feel young, I feel vibrant, and when you're in condition you want to do it. But when you're not in condition you just want to throw it out the window."

Tyson has fought only 11 rounds since returning from suspension in January 1999. Nielsen has fought 82 rounds in that span. He's also fought four times since Tyson's last fight a year ago, a no-decision two-rounder against Andrew Golota.

Saturday is supposed to be another walkover, probably lining Tyson up for a title fight against the winner of the Nov. 17 bout between Hasim Rahman and Lennox Lewis. The winner of the Evander Holyfield-John Ruiz bout set for December is also a possibility.

Tyson said he'd prefer to fight Rahman because he's easier to hit, though he also has a "score to settle" with Holyfield. And Lewis would be an easier fight to arrange since -- unlike Rahman -- he's not managed by Don King.

"It would be unrealistic to say this will be a blowout," said Tyson trainer Tommy Brooks. "But me, personally, I'm 99.99 percent sure Mike is going to stop this guy."

In the past, Tyson has used antidepressants, with the medication tapering off as the fight nears.

"I don't know if he's taking medication or what. ... I don't have a clue," Brooks said.

Tyson's longtime friend Jay Bright said: "That's a medical thing for him and his doctor to gauge."

Nielsen, 36, is a year older than Tyson and regarded as "very hittable," although he's been knocked down only once in his professional and amateur career. At 6-foot-2 and usually fighting at 250 pounds, he has KO wins over ex-heavyweight champions Tim Witherspoon and Tony Tubbs. He also outpointed former champion Larry Holmes.

Nicknamed "Super Brian" or the "Danish Pastry," he's enormously popular in Denmark where he's expected to drive a 47,000 sellout Saturday under the roof at Parken Stadium -- the biggest boxing event in Danish history.

"My hat's off to Brian because he's the only one who stepped up the plate to fight Mike," Brooks said. "But Brian has never fought a guy that can blast like Mike. Mike can tear down a wall with either hand."

"I've heard people say he is not what he used to be, he's only a fraction of what he used to be," Brooks said. "The five fights I've been with him, there'll all knockouts. What else can you ask for?"

Tyson, who usually fights in the 215-222-pound range, probably will be at least 230 for Thursday's weigh-in, Peterson said.

"Even more than that would be fine," he said. "None of it is fat."

Peterson said Tyson ballooned to a pudgy 250 when they started working four months ago. Tyson said his attitude has soared as he's shaped up.

"I don't know if Mike could go 48 minutes in the NBA, but he's fit, very fit and his body fat is down," Peterson said.

Tyson, who admitted his age was catching up with him, said he was discouraged when out of shape.

"Sometimes I couldn't walk around the block without huffing for air," he said.

Tyson said he planned to stay in Europe after the fight, perhaps setting up a training camp in Europe. The native New Yorker said he wasn't ready to go home following the terrorist attacks a month ago.

"I grew up with all those buildings, seeing those building," he said of the Twin Towers. "I had no idea what they were, but they were taller than the Empire State Building. I remember being on the roof of my pigeon coop looking at them from Brooklyn."