FRANKFURT, Germany – Facing a six-month recovery after tearing a ligament in his knee, WBC heavyweight champion Vitali Klitschko came to a tough realization: It was time to retire.

“Unfortunately, I’ve been fighting injuries recently more than facing rivals in the ring,” Klitschko said yesterday in a statement. “The decision to end was hard to make. But I would like to end my career on top and with my retirement make the way free for my successor.”

The 34-year-old Klitschko pulled out of Saturday’s title defense against Hasim Rahman in Las Vegas because he hurt his knee last week in training. The WBC said earlier this week that Rahman would be given Klitschko’s title should the Ukrainian fail to defend it within three months.

Yesterday, WBC president Jose Sulaiman said the organization’s Board of Governors will now vote on awarding the title to Rahman, who was more than ready to accept it.

“I am thrilled that WBC president Jose Sulaiman is keeping his promise to me by convening his Board of Governors to automatically upgrade me from interim champion to again become the undisputed WBC heavyweight champion,” Rahman said.

Klitschko’s statement said the knee was examined Tuesday, and that he underwent arthroscopic surgery. Bob Arum, who was supposed to promote Saturday’s Klitschko-Rahman fight, said he talked to Klitschko Tuesday and tried to talk him out of retiring. But he said Klitschko had no desire to go on.

“He said he was 34 and his body was betraying him,” Arum said. “He didn’t want to put up with these betrayals from his own body anymore.”

The 6-foot-8-inch Klitschko, who made only one title defense, sometimes had an awkward, stiff style, but packed a powerful punch, especially in his right hand.

His retirement means the Klitschko brothers won’t realize their ambition to share the heavyweight championship.

It also means the top heavyweight champions are all controlled by promoter Don King, who said he wanted Rahman to defend the title against James Toney and for the winner to join the other title holders in a tournament to crown a real heavyweight champion.

Wladimir Klitschko, Vitali’s younger brother, got back into contention in the division when he beat Samuel Peter in a unanimous decision in September in an IBF elimination bout. The victory made Wladimir the mandatory challenger to IBF champion Chris Byrd.

Vitali, who hadn’t fought since stopping Danny Williams in the first defense of his title last December, was first supposed to have met Rahman in April.

But the fight was postponed when Klitschko pulled a thigh muscle, and initial attempts to reschedule it were stopped when he injured his back.

Sulaiman said earlier this week that the latest cancellation was the fourth time Klitschko (35-2,34 knockouts) has backed out of a fight with Rahman (41-5-1, 33 KOs), and hinted that he might be looking for excuses to stay out of the ring with the American.

Rahman, a former heavyweight champion, grew so tired of waiting to meet the Ukrainian that he fought Monte Barrett in August. He won on a decision to become the WBC interim champion.

Klitschko is the second WBC heavyweight champion in a row to retire while holding the title. Lennox Lewis quit in February 2004 after beating Klitschko in his last fight. Klitschko’s other loss, when he also was forced to quit because of an injury, came in April 2000 to Byrd.

Lewis was the first reigning world heavyweight champion to quit since Rocky Marciano in 1956.The only other fighter to do so was Gene Tunney in 1928. Klitschko stopped Corrie Sanders in the eighth round in April 2004 to win the WBC belt.

Klitschko was involved in a steroid controversy that prevented him from taking part in the 1996 Olympics. Instead, Wladimir took his place and won the gold medal for Ukraine. In his biography, released in Germany in 2004, Vitali said he used steroids after aggravating a leg injury sustained during a kickbox bout. He tested positive and was thrown off the Ukrainian team.