MUNICH, Germany – Ukrainian Wladimir Klitschko stopped Derrick Jefferson in the second round, sending the American to the canvas three times Saturday while retaining his WBO heavyweight championship.

Klitschko, the 1996 Olympic super heavyweight champion, dropped Jefferson for the first time in the round with a straight right. The punch caught Jefferson on a left eye swollen from a first-round knockdown.

"It went the way I wanted it to," said Klitschko, now 36-1 with 33 knockouts. "I used his mistakes. That is what boxing is all about."

Jefferson, 24-3-1 with 20 knockouts, struggled to his feet, but stumbled around wildly until Klitschko sent him back down. The blows didn't look clean, but the American was having trouble staying on his feet.

Klitschko, who turns 25 Sunday, hopes to fight Lennox Lewis, who holds the WBC and IBF titles.

"If it's this year or next, I don't care," Klitschko said. "The most important thing is he doesn't retire."

He'd like to fight Lewis in the U.S.

"Hello America, we're coming," promoter Hans-Peter Kohl said Klitschko, already a huge draw in Germany and a folk hero in his homeland.

Klitschko won the lightly regarded WBO title in October by pounding American Chris Byrd over 12 rounds.