Spike takes you behind the scenes of the Las Vegas tryout for Season 13 of “The Ultimate Fighter.” It’s a pressure cooker with hundreds of aspiring fighters getting just a few minutes to show off their skills.

Included this bunch, that showed up back in November at the Red Rock Casino, were a 51-year-old, a K-1 veteran coming back from open heart surgery and a U.S. Army captain, who just returned from Iraq in April.