BOSTON -- Chael Sonnen snapped a two-fight losing streak with a first-round submission victory over former Ultimate Fighting Championship light heavyweight champion Mauricio "Shogun" Rua on Saturday night at the TD Garden in a scheduled five-round non-title bout.
Sonnen (29-13-1) earned the victory at 4:47 of the first round when he applied a guillotine choke.
"He submitted Shogun," UFC President Dana White said. "That's something I don't think anyone saw coming."
Rua, from Brazil, dropped to 21-8.
Midway through the round, Sonnen took Rua to the mat with a double underhook throw. After he landed several head strikes while on top of Rau, Sonnen turned Rua over with Rua's head locked under his arm, forcing Rau to tap out.
"It was a hard fight," Sonnen said. "I got caught in a position where I was not able to land a lot of shots. I threw a lot that missed. If he caught me in a guillotine, I would have tapped. I had him and he couldn't slip out. It was the first round and we're not slippery. If the roles were reversed, I would have tapped, too."
The 36-year-old Sonnen, from West Linn, Ore., lost by technical knockout in his last two fights to Anderson Silva and Jon Jones.
The 31-year-old Rua dropped two of his previous three bouts, with decision losses to Dan Henderson and Alexander Gustafson and a TKO victory over Brandon Vera.
The bout was the main event of the debut of the UFC Fight Night Series on Fox Sports 1.In the UFC's second promotion in Boston, the card drew a crowd of 12,539.
In the co-main event, heavyweight Travis Browne of Albuquerque, N.M., knocked out Alistair Overeem of the Netherlands at 4:08 of the first round in a scheduled three-round bout.
Browne dropped Overeem with a left front kick to the face. Browne followed up with three right hands to the head before referee Mario Yamasaki stopped the fight.
"I'm not trying to take anything away from my performance but we expected this," Browne said. "I didn't know I was going to get my butt kicked for the first few minutes but everything else went like we thought it would. I was mentally there but I've never had my body shut down like that on me.
"The referee kept saying he was going to stop it and I was telling him that I was ok. I was thinking about my sons and providing for my family, this is what I'm made of."
Brown improved to 15-1-1. Overeem dropped to 36-13, with one no contest.
Former World Extreme Cagefighting featherweight champion Uriah Faber of Sacramento, Calif., won a three-round unanimous decision against Iuri Alcantara of Brazil.
In the opening minute of the fight, Alcantara threw Faber to the mat, but after Faber reversed positions, he was in control for the rest of the fight. Faber kept Alcantara on the mat for most of the final two rounds, landing several punches to the head.
In a scheduled three-round welterweight bout, Matt Brown of Columbus, Ohio, knocked out Mike Pyle of Las Vegas at 29 seconds of the first round.
Boston's John Howard won a three-round split decision over Uriah Hall of New York at middleweight.
In the opening bout of the main card, lightweight Michael Johnson of Boca Raton, Fla., won a three-round unanimous decision over Joe Lauzon of Bridgewater, Mass.