WWE Superstar Daniel Bryan's career may be cut short prematurely.

"The Beard" has been sidelined due to a concussion since April and WWE doctors have yet to clear him. Bryan admitted that he isn't sure if he'll ever be able to return to the squared circle again due to the ailment.

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"I think it could be the end of my career in WWE, but I don't think it will be the end of my career," Bryan told The New Paper Online. "I could find another passion, but it would just be sad because this is what I have been most passionate about since I was 5."

Bryan has had a tremendous ride from scrappy underdog to top dog in the WWE, and the "Yes Man" has left the WWE Universe with many great memories. Still, you never want to see a promising career cut short to a serious injury, especially since Bryan is only 34.

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If it is the end of the line, it's been a great run for Bryan and here is a look at his five best WWE moments.

5) Team Hell No

Perhaps Bryan was never more entertaining than when he joined forces with Kane to form the most dysfunctional tag team in WWE history. Between Bryan's "No Movement," the constant bickering between the partners and their need for therapy, it was an entertaining run. Despite all their storyline problems, they held the tag gold for 245 days.

4) Comeback Kid

This isn't Bryan's first run-in with a serious injury. The WWE Superstar was sidelined with a debilitating neck injury in May 2014 that sidelined him for the rest of the year. Bryan returned in early 2015 and triumphantly announced that he was making a comeback at the Royal Rumble. From there, he had a memorable match against Roman Reigns at Fastlane and captured what could be his final belt -- the Intercontinental Championship -- in a ladder match at WrestleMania 31.

3) World Heavyweight Champion

Bryan shocked the world when he won the Money in the Bank Ladder Match in 2011 and after several teases, he eventually cashed the contract in. Though he promised to cash-in at WrestleMania, "The Beard" decided to prey on a fallen Big Show at TLC at the end of the year, capturing the big gold belt for the first time and holding it for 105 days.

2) Hanging With The Best

The bearded one finally got a chance to shine for good in the main event scene when he took on John Cena at SummerSlam in 2013 for the WWE Championship. The two had a tremendous match, and in the end Bryan defeated the face of the franchise right in the middle of the ring. The celebration was short-lived thanks to a Triple H heel turn (creating The Authority storyline) and Randy Orton cash-in, but he'll always hold that win over the "Cenation" leader.

1) YESleMania

Bryan's greatest moment came at the biggest spectacle on the WWE's calendar. The company simply couldn't deny the YES Movement, so it went against its original plans of having Batista go over Orton for the WWE World Heavyweight Championship and thrust Bryan into the main event after he defeated Triple H in the opening bout of the evening. Bryan then went on to defeat the two former Evolution stablemates to capture the title as confetti rained down at a raucous Mercedes-Benz Superdome. It was truly the pinnacle of Bryan's career and his greatest crowning moment.

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