Dec. 30, 2011; Las Vegas, NV, USA; UFC fighter Brock Lesnar after announcing his retirement following a heavyweight bout at UFC 141 at the MGM Grand Garden event center. Mandatory Credit: Mark J. Rebilas-USA TODAY Sports Dec 30, 2011; Las Vegas, NV, USA; UFC fighter Brock Lesnar leaves the octagon after being defeated by Alistair Overeem (not pictured) during a heavyweight bout at UFC 141 at the MGM Grand Garden event center. Lesnar retired following the loss. Mandatory Credit: Mark J
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