An untimely knee injury has forced UFC Welterweight Champion Georges “Rush” St. Pierre out of his main event bout with “The Natural Born Killer” Carlos Condit at UFC 137 on October 29th in Las Vegas, Nevada. UFC President Dana White announced the news and additional updates today.

The co-feature between former two-division UFC champion “The Prodigy” B.J. Penn and ex-Strikeforce champion Nick Diaz has now been promoted to headline the card. Penn and Diaz will square off in a three-round battle. Condit is expected to remain on the sidelines until St. Pierre is healthy.

St. Pierre (22-2-0) had initially been set to face off with Diaz (25-7-0, 1 ND) in a champion versus champion bout on the card, but Diaz was removed from the fight after failing to show up for mandatory press conferences promoting the event. A reshuffling followed and Diaz was matched up against Penn (16-7-2), while Penn’s original opponent, Condit (27-5-0), stepped up to face St. Pierre in a title tilt.

With St. Pierre now off of the card, White announced that the UFC would keep Condit on the sidelines until the champion has healed. Condit will most likely receive his UFC title shot against St. Pierre in his next fight. Penn and Diaz will face off in the new UFC 137 main event. The change comes mere weeks after Diaz was demoted from the original main event when White felt that he could not trust the former Strikeforce titleholder to show up.

Whether the pressure of headlining a UFC card affected Diaz earlier this year or not, he now once again finds himself in the main event at UFC 137. The event, now dubbed “Penn vs Diaz,” takes place on October 29th at the Mandalay Bay Events Center in Las Vegas, Nevada.

(Photo Credit: Sherdog.com)