Ukraine's Vladimir Klitschko retained his heavyweight world titles with a points victory over Russian challenger Alexander Povetkin in Moscow's Olimpiyskiy stadium tonight.

The 37-year-old Klitschko, whose record improved to 61 wins and three losses, knocked Povetkin, undefeated in his 26 previous fights, down four times to earn a unanimous points victory and hold on to his WBA, IBO, IBF and WBO crowns.

Klitschko's older brother, Vitali, holds the WBC belt.

"Alexander is a fighter and it was hard for him because I hurt him. But he stuck in there because he has a big heart," said Vladimir in a ringside interview.

"I wanted to finish it earlier. I wanted to land that one big punch and I think I could have done better."