The UFC's top two middleweight contenders, Nate Marquardt and Chael Sonnen, collide in a match that will move the winner one step closer to a UFC world title shot.

Two of the game's 170-pound stars, former champion Matt Serra and two-time title challenger Frank Trigg will meet for the first time.

UFC 109: Relentless, Saturday, February 6, live on pay-per-view from the Mandalay Bay Events Center, in Las Vegas, Nevada.