One of the marquee welterweight fights at UFC 158 just fell apart. Canadian Rory MacDonald has been forced out of his bout with Carlos Condit due to an injury. MMA Fighting's Ariel Helwani has the news:

According to sources close to the fight, MacDonald suffered an undisclosed injury in training, which has forced him to withdraw from his fight against Condit at UFC 158. No opponent has been signed to replace MacDonald against Condit next month. As of now, he is still expected to compete on the card.

MacDonald (14-1) was looking to avenge the only loss of his career in a rematch with Condit (28-6). It remains to be seen if the UFC will decide to break up the third big welterweight fight on the card, Jake Ellenberger vs. Johny Hendricks, and promote one of them into the fight with Condit or if they will bring in someone who wasn't originally scheduled for the card. UFC president Dana White stated that the card was welterweight-heavy in case something like this happened, but we'll have to wait and see.

The card will be main-evented by a UFC welterweight title fight between champion Georges St. Pierre and former Strikeforce champ Nick Diaz.

UPDATE: According to Damon Martin of Bleacher Report, MacDonald suffered a neck injury in training and pulled out of the bout over ther the weekend.

UPDATE 2: The MMA Fighting story was updated with a statement from MacDonald's manager Lex McMahon regarding the injury: