LAS VEGAS (AP) - Middleweight champion Chris Weidman has a knee injury, forcing the UFC to postpone his title bout against Lyoto Machida for six weeks.
The UFC announced the changes to two major Las Vegas shows on Monday.
Weidman (11-0) was expected to make his second title defense at UFC 137 on May 24 at the MGM Grand Garden, but the Long Island-based mixed martial artist needs minor surgery.
Weidman's bout with Machida is moving to UFC 175 on July 5 at the Mandalay Bay Events Center.
The UFC hasn't decided on a new main event for UFC 173, its traditional Memorial Day weekend card.
Weidman claimed the 185-pound title when he stopped long-reigning champion Anderson Silva last July. He defended the belt in December when Silva broke his leg in their rematch.