Coming off three straight victories, Jake Ellenberger uses his heavy hands to knock out Sean Pierson in the first round. Ellenberger looks to stay at the top of the division as he takes on Kelvin Gastelum in the co-main event at UFC 180 in Mexico.

Jake Ellenberger steps in on short notice to fight Sean Pierson at UFC® 129. Watch the fight here for free!

Watch the official weigh-in for UFC 141: Lesnar vs. Overeem.

UFC® 129 Prelim Fight: Sean Pierson vs Jake Ellenberger

Rewatch all of the action of the UFC 129 Weigh-In. Don't forget to watch UFC 129 Saturday night St-Pierre vs. Shields at a NEW TIME 9 pm ET/6 pm PT.

The action will be "relentless" as Nate Diaz faces Rory MacDonald, and Jake Ellenberger battles Sean Pierson - live and FREE on Spike TV!

The road to the Octagon took Sean Pierson 14 years to trek, but he arrived to get a win in a crowd-pleasing, all-out war with Matthew Riddle.

UFC® 124 Prelim Fight: Matt Riddle vs Sean Pierson