WATCH: Wladimir Klitschko Knocks Out Kubrat Pulev

So much for Kubrat Pulev posing a serious threat to Wladimir Klitschko’s heavyweight titles.

Pulev, an unbeaten Bulgarian billed by some as the most serious challenger Klitschko has faced in years, lasted only five rounds before Klitschko knocked him out with a left hook, extending his eight-year reign as the world’s top heavyweight.