Berlin - Vitaly Klitschko returns into the ring after a four-year absence on Saturday, full of confidence he can claim the World Boxing Council heavyweight world title against holder Samuel Peters of Nigeria.

"I am fit and I am confident. You have to stay relaxed," said Klitschko on Friday after the weigh-in for the Berlin bout.

Klitschko, 37, carries the honour of WBC "emeritus champion" after retiring in 2005 over injuries including a ruptured knee ligament. The special status allowed him a title bout in his comeback fight.

His 37th and last bout so far was a title defence in December 2004 against Briton Danny Williams. Klitschko has only lost twice in the ring and despite his confidence said he won't underestimate Peters.

"It won't be an easy fight, he is ready," said Klitschko, who had originally planned his comeback last year.

"The injuries are in the past ... I didn't lose my title in a fight. I gave it up three years ago. But now I want my title back."

Peters has lost once in his 31 bouts, against Klitschko's brother Vladimir, the International Boxing Federation and World Boxing Organization world champion.