#3 Roman Reigns
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Before this year's WrestleMania, most fans presumed that Roman Reigns was going to be the one to finally topple Brock Lesnar, and in all fairness, it probably would have been a good idea, at the time.
Unfortunately for Reigns, his credibility has been severely damaged by two back to back defeats against The Universal Champion. While the WWE is prone to just pushing Roman Reigns to the title scene at any given moment, it seems like they have gone cold on the idea of having him be the one to defeat Lesnar.
Reigns will still be back in the title picture before the end of the year, and there is always the very possibility that the WWE will pull a 180 and push him to a title shot at SummerSlam but for now, it seems like he will be occupying a spot in the upper mid-card for the next few months.