#1. Vladimir Kozlov defeated The Undertaker on Smackdown in 2009
During an episode of Smackdown in 2009, Vladimir Kozlov defeated The Undertaker clean via pinfall. Kozlov was hyped as the next great monster when he was brought into WWE. He was only a few weeks into his run when he pinned The Phenom after reversing "Old School."
The Moscow Mauler soared higher after his win against Taker. He continued to rack up wins over the rest of the roster, and despite the lack of fan fare, Kozlov eventually found himself in the WWE title picture.
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His attempts at the title failed. Kozlov slowly faded down the card as it became more apparent he wasn't quite ready for the push he received. He would eventually find himself in a comedy tag team with Santino Marella. They would win the tag titles together, which basically amounted to the climax of Kozlov's WWE career.
Kozlov was always meant to be a monster in WWE. It made sense for him to pick up a win over The Undertaker. However, when one looks back upon that moment now, it's a bit surprising considering where his career ended up. Sometimes not even a win over The Undertaker himself can save your career.