Roy Nelson stops Matt Mitrione

Roy Nelson's right hand helped seize the day once again.

Nelson needed less than three minutes to knock out Matt Mitrione in the main event of "The Ultimate Fighter 16" finale at The Hard Rock Hotel and Casino.

He caught Mitrione walking forward with a right uppercut, which he followed with a perfectly placed left hook. With Mitrione covering up along the fence, Nelson finished the fight at the 2:58 mark with a series of unanswered right hands.

Pressing the action seemed to be part of Nelson's game plan early. He moved forward throughout, forcing Mitrione to fight off his heels. Nelson did look to take things to the floor after catching a leg kick, but Mitrione fought off the attempt.

Teammates on the 10th season of the TUF reality series, Nelson and Mitrione shared a friendly exchange after the fight.

It's yet another knockout win for Nelson (18-7) courtesy of his right hand. Since joining the UFC in 2009, all five of his victories have been knockouts, including four in the first round.

Mitrione (5-2), coming off a 14-month layoff, lost his second straight fight. He suffered a unanimous decision loss to Cheick Kongo in October 2011. Mitrione stepped up as a late replacement for the injured Shane Carwin, who coached opposite Nelson during Season 16 of TUF.

Smith decisions Ricci in upset

Colton Smith became the latest winner of "The Ultimate Fighter" reality series, defeating Mike Ricci via unanimous decision in their welterweight finale.

With the exception of a little late drama in the final minute, it was a dominant, gritty performance for Smith. All three rounds were nearly identical, with Smith closing the distance, slamming Ricci to the floor and threatening with submissions.

All three judges scored it a clean sweep for Smith: 30-27, 30-27 and 30-26.

Ricci managed to mount one late attack, taking Smith's back during a scramble and setting up an armbar attempt in the final minute of the fight. The drama wouldn't last, though, as Smith escaped and finished the round in dominant position.

An awkward moment occurred in the second round, when Ricci winced and motioned to referee Steve Mazzagatti that he'd been hit with a low blow. With no foul called, Smith charged forward only to be caught by an unexpected counter by Ricci.

Fans grew restless with Smith's strategy late in the fight, but it was dominant nevertheless. He came close to securing a rear-naked choke several times throughout the fight and threatened with an arm triangle in the final round.

For Smith (4-1), it's the first decision win of his career. His prior three wins all came via submission in the first round. Ricci (7-3) drops his official UFC debut, but probably will continue in the Octagon as a lightweight.

Barry bludgeons Del Rosario

Pat Barry recorded the seventh knockout of his career in stunning fashion, tagging Shane Del Rosario with a left haymaker early in the second round.

Del Rosario somehow stayed on his feet, but couldn't hide the effects of the punch. He staggered backward as Barry gave chase. Two more right hands along the fence and one final left from Barry officially ended the heavyweight fight 26 seconds into the round.

It was clear from the start Del Rosario preferred not to stand. He spent much of the first round working for single legs, even prompting referee Kim Winslow to separate one stalemate along the fence.

Barry found himself in trouble once, after giving up his back to Del Rosario during a scramble. With under a minute left in the first round, Del Rosario worked for a rear-naked choke, armbar and omaplata but ultimately ran out of time.

"I'm either going to win all the way or lose all the way," Barry said. "I go out there throwing 'Thunda.'"

Barry (8-5) scored a badly needed win, as he had dropped three of his last four fights. He posted a first-round knockout over Christian Morecraft in January, but followed that with a first-round loss to Lavar Johnson in May.

Del Rosario (11-2) has now lost two straight. He suffered a second-round TKO loss to Stipe Miocic at UFC 146.

Poirier submits Brookins

Featherweight Dustin Poirier got back in the win column with a first-round submission victory over Jonathan Brookins, but it was anything but easy.

Looking to bounce back from a loss to Chan Sung Jung in his last outing, Poirier got off to a bad start when he was tagged during a wild exchange in the opening minute.

Brookins moved in to swarm him along the fence, but Poirier eventually survived, tying Brookins up in the clinch and slowing the action.

It didn't take long for Poirier to turn the tide. A counter-short right hand dropped Brookins moments later. Poirier used the opportunity to sink in a D'Arce choke, forcing Brookins to tap at the 3:15 mark.

"We started off at a quick pace there," Poirier said. "I think we both decided to get the party started a little early ... I didn't expect him to tag me like he did but that was probably because of me leaving so many openings."

Poirier (13-2) has now won six of his last seven fights, including four finishes. Brookins (13-6) drops consecutive fights for the first time in his career. He suffered a second-round submission loss to Charles Oliveira in June.