(REUTERS)-Wladimir Klitschko stopped Italian challenger Francesco Pianeta in six rounds to retain his world heavyweight titles in Mannheim, Germany.

Ukrainian Klitschko selected the previously-unbeaten Pianeta as his optional title defence, granted by the authorities on condition he agrees to fight World Boxing Association (WBA) ‘regular’ champion Alexander Povetkin this summer.
The cancer-survivor challenger had previously served as a sparring partner for Wladimir, and the bout proved to be little more than another practice session between the two, albeit one which will go down in the record books as Klitschko’s 60th professional win and his 18th in succession.
Pianeta attempted to find a way through to Klitschko’s body in the opening round, but despite landing a couple of decent early shots he was under constant barrage from trademark jabs and straights from ‘Dr. Steelhammer’ which soon wore the challenger down.
As his reserve diminished, so did his willingness to take chances, but in typical Klitschko fashion there was no sight of the champion going in for the kill until he was absolutely certain he could not be caught out on the counter.
Flash knockdowns came in the fourth and fifth rounds but Pianeta was not fit to return for more punishment and referee Ernest Sharif called a halt to the fight.
Klitschko will now proceed to Russia for a monster £14.77 million purse, of which he will receive over £11 million, against Povetkin by the end of August.