Chael Sonnen returned to action over the weekend, competing against Andre Galvao in the main event of Metamoris 4. Sonnen, who retired from MMA and the UFC earlier this year after two failed drug tests, was submitted when Galvao locked in a rear-naked choked.

Recently, Sonnen appeared to be a potential no-show for the event after the Nevada Athletic Commission threatened to fine him for each failed test if he elected to compete in Los Angeles at the grappling event. However, true to his word, the former three-time UFC title contender showed up.

In other action, UFC heavyweight Josh Barnett submitted Dean Lister and Vinny Magalhaes fought Keenan Cornelius to a draw.

Palomino knocks out Gonzalez at WSOF 12

In the main event of World Series of Fighting 12, Luis Palomino delivered a first round knockout of Lewis Gonzalez.

The card took place from Las Vegas, with the main card airing on NBC Sports Network.

Gonzalez lost for the first time in his career.

In other action, Ronny Markes earned a decision over Cully Butterfield, as did Elvis Mutapcic vs. Kelvin Tiller. Brandon Hempleman and Matt Sayles completed the televised action with decisions.