HAMBURG, Germany — Vitali Klitschko punished Shannon Briggs for 12 brutal rounds and retained his WBC heavyweight title with a unanimous decision on Saturday.

The Ukrainian champion dominated the action but couldn't knock down the American challenger.

"I am very surprised by how much he took," Klitschko said. "He's got a huge heart."

The judges scored it 120-107, 120-107 and 120-105 for Klitschko, who improved to 41-2. Briggs dropped to 51-6, with one draw.

"I've fought George Foreman, I've fought Lennox Lewis and Vitali's the best," Briggs said. "He hits harder than Foreman, he's got incredibly fast hands.

"This was my best fight."

Klitschko said Briggs, at 38 one year younger, deserved "a lot of respect."

"I could not believe he was still standing after taking so many punches," Klitschko said.

Klitschko used his left jab to open up Briggs' guard, landing a big right two minutes into the opening round.

Two left hooks found Briggs' chin early in the second round and the Ukrainian landed some more rights, while Briggs sought to hurt Klitschko with blows to the body without much success.

Klitschko connected with several combinations in the third but Briggs also found the target with counter-punches. The champion scored with a good right hook late in the round. He also finished the fourth strongly, landing a few good punches to Briggs' head.

Briggs connected with a couple of good rights in the fifth, his best round, but also had to absorb several hard hits from Klitschko.

Klitschko hit the American repeatedly with left-right combinations in the sixth, but Briggs showed no signs of being shaken.

Klitschko's big punches began to wear down Briggs midway through the seventh and the American was taking heavy punishment before the round was over. Briggs was saved by the bell after taking two big rights that clearly staggered him.

Briggs stayed upright in the eighth despite taking more heavy blows to the head, and finished the ninth even though Klitschko connected with two huge rights and a left hook late in that round.

The American was little more than a punching bag for Klitschko in the 10th. Briggs hardly rose his hands in defense midway through the 10th but Klitschko still could not put him down despite hitting Briggs at will.

Briggs surprised Klitschko with a clean right in the next. Klitschko replied with two big rights of his own that snapped back Briggs' head. But the American only shook his head and stayed up.

Klitschko went for the knockout in the final round but Briggs withstood everything. (AP)