ATLANTIC CITY, N.J. -- Wladimir Klitschko might be headed for better things, and Ray Mercer for boxing oblivion after their WBO heavyweight championship fight Saturday night.

	Wladimir Klitschko, right, holds up his WBO title belt with his brother, Vitali Klitschko, after stopping Ray Mercer.

The 26-year-old Klitschko retained his title, stopping Mercer in the sixth round of a scheduled 12-rounder.

"I'm ready for the big fight,'' Klitschko said. "I hope the next fight will be against Lennox Lewis.''

Lewis, who knocked out Mike Tyson earlier this month, holds the WBC and IBF titles.

Mercer doesn't have to worry about any big fights, and thinks Klitschko might have a little more to learn before he steps up too far.

"I'm 41 years old,'' Mercer said. "If he wants to claim a big victory, let him. But I'm not finished.''

The up-and-coming Ukrainian (39-1) knocked down Mercer in the first round and cut him in the fifth, using a powerful left jab that kept the rugged Mercer on the defensive throughout.

In the sixth, Klitschko backed Mercer into the ropes and unloaded a hard right hand that snapped Mercer's head back and seemed to take the fight out of him.

Mercer (30-5-1) moved to the other rope but when Klitschko unloaded another flurry of punches and the blood streamed down Mercer's face. Referee Randy Neumann stepped in, ending it at 1:08 of the round.

"I never faced a guy with such a strong chin,'' Klitschko said. "It's the strongest chin in the world.''

The performance by the 6-foot-7-inch, 243-pound Klitschko might cement his reputation as the heavyweight division's next big thing.

He was powerful, quick, he took a punch -- Mercer gave him a welt over the right eye -- and he fought with the kind of fluid motion that many eastern European fighters lack.

In stopping Mercer, he did what no other fighter had ever done. In knocking him down, he did what only one -- Evander Holyfield -- had ever done.

"I got beat, fair and square,'' Mercer said. "He caught me with a big punch in the first round and I never regrouped.''

Punch statistics reflected the degree of domination: Klitschko connected on 193 of 429 punches, to 54 of 124 for Mercer, according to CompuBox.

The fight was in some respects a do-or-die proposition for both.

Mercer, the well-traveled former Olympic champion who has fought -- but not beaten -- the likes of Lewis, Holyfield and Larry Holmes, needed a victory to keep his flagging career alive.

Klitschko, whose pedigree includes a doctorate degree in sports science and philosophy, had little to win and a lot to lose.

A win would keep him on track for a shot at the titles Lewis now holds. But a loss to the aging Mercer could have caused his stock to drop.