LOS ANGELES -- Vitali Klitschko was bloodied but still willing. He had given Lennox Lewis all he wanted and more, yet after six rounds he sat bleeding on his stool as a ring doctor ended his chance of becoming heavyweight champion.

Klitschko hurt Lewis during six brawling and sometimes brutal rounds, exposing him as an aging fighter. He answered questions about his heart and talent, while raising many about the future of the heavyweight champion.

About the only thing he didn't do Saturday night was win the heavyweight title. That still belonged to Lewis after the fight was stopped because of a bad cut over the challenger's left eye.

"He is a great fighter. I won this fight in points,'' Klitschko said. "I want a rematch. I showed everybody that I can fight Lennox Lewis.''

An entertaining fight ended on a sour note when the ring doctor ordered it stopped after the sixth round. Klitschko was winning the bout on all three scorecards.

Klitschko, bleeding badly from a cut over his left eye, jumped off his stool in disbelief, yelling "No, no, no'' and going across the ring toward Lewis as if he wanted the fight to continue.

Lewis was tired, but more than willing.

"If the fight went on, I would have knocked him out,'' Lewis said. "There is no way he could have finished the fight. He was just deteriorated anyway.''

Klitschko hurt Lewis in the early rounds and was more than holding his own in a fight that magnified both the ring rust Lewis had from not fighting for a year and the unmistakable fact he was a 37-year-old heavyweight in the ring.

All three ringside judges had Klitschko winning 58-56, but the AP had it 58-56 for Lewis. Ring doctor Paul Wallace looked at Klitschko's cut and ordered referee Lou Moret to stop the fight.

"I can see very well,'' Klitschko complained. "I don't know why the doctor stopped the fight.''

The crowd at Staples Center booed wildly, and Klitschko held his arms up in victory and pointed to his heart. It was his heart that had been questioned when he quit on the stool between rounds against Chris Byrd after injuring his shoulder.

"Right now I feel like the people's champion,'' Klitschko said. "I did not want them to stop the fight. My strategy was to take it into the seventh or eighth round and my strategy was working perfectly.''

Klitschko went into the fight a 4-1 underdog and wasn't even supposed to be the best fighter in his family. That honor belonged to his brother, Wladimir, who worked his corner against Lewis.

But the 6-foot-7 Ukrainian came out and traded punches from the opening bell, rocking Lewis in the second and third rounds and hitting him with almost every left jab he threw. Lewis looked tired and old, but did enough to come back and land uppercuts and right hands.

"We are big guys and any punch is going to hurt,'' Lewis said. "I do give him credit. I gave him a chance to fight. He has an unusual European style. I was just getting my second wind.''

One big right hand appeared to open a cut in the third round that proved to be the undoing of Klitschko. Because the cut was caused by a punch and not a head butt it didn't matter that Klitschko was leading on the scorecards when the fight was stopped.

Wallace said he stopped the fight not because of the blood, but because Klitschko's eyelid was covering his eye and he had to move his head to see.

"When he raised his head up, his upper lid covered his field of vision,'' Wallace said. "At that point I had no other option but to stop the fight. If he had to move his head to see me, there was no way he could defend his way against a punch.''

The normally mild mannered Klitschko, who speaks four languages and holds an advanced college degree, was visibly angry and had to be restrained by his brother at one point.

He's not likely to get a rematch, assuming Lewis continues to fight. Lewis is eyeing a possible bout with Roy Jones Jr. later this year that could mean huge money for both fighters.

Jones would have to be encouraged after a fight between two big men for the WBC title. Klitschko was trying to become the tallest heavyweight champion ever and the two fighters combined for a record 504½ pounds between them.

Lewis weighed 256½ pounds, the heaviest of his career, and he appeared soft in the middle. For one of the few times in the 6-foot-5 champion's career, he was punching up at an opponent.

"I knew his condition was not good, he's very heavy. He couldn't fight hard,'' Klitschko said. "I know I was hurting him with my punches.''

Klitschko landed a big right hand 1:45 into the second round that shook Lewis, whose chin had been questioned after being knocked out by Oliver McCall and Hasim Rahman in other title fights.

"He woke me up,'' Lewis admitted.

Lewis had a vast edge in experience, coming into the fight with 15 wins in 17 title fights. He had been off a year, but seemed to be in his prime at a time when most fighters are in decline.

Lewis became only the third heavyweight champion his age or older to successfully defend a title, but he looked every bit his age.

Still, he came on to win the sixth round and he was more than willing to trade big punches in the middle of the ring with Klitschko. The fight was marred by a lot of holding but it excited the 15,939 fans gathered for the first title fight in Los Angeles in nearly 45 years.

"It was only a matter of time. He was deteriorating. The referee saved his face,'' Lewis said.

Both fighters appeared tired, but Klitschko was the fresher puncher as the fight continued. But after he was cut midway through the third round it seemed only a matter of time before the fight would have to be stopped.

The ring doctor looked at the cut after the third round and allowed the fight to continue. But the cut reopened and was bleeding badly in the sixth round. The doctor went over to the corner and ordered the fight stopped.

"I was getting to him. Just look at his face,'' Lewis said. "I was going to stop him.''

Klitschko was fighting for a major title for the first time and fighting in the United States for only the second time. Klitschko spent much of his career fighting on cards in Germany with his brother, and his record was littered with a string of unheralded opponents.

Klitschko was a 4-1 underdog against a champion who looked devastating when he stopped Mike Tyson in the eighth round a year ago.

Many in boxing wondered if Klitschko had the heart or the talent to stay in the ring with the heavyweight champion.

They weren't wondering after he gave Lewis everything he had and more in a fight he had taken on two weeks notice.

The way the fight unfolded won Klitschko not only fans in the arena, but one from across the ring.

"He's a legitimate No. 1 contender,'' Lewis said.

Lewis, who earned a reported $10 million, improved to 41-2-1, 32 knockouts. Klitschko is 32-2 with 31 knockouts.