Jan. 31--Ultimate Fighting Championship middleweight champion Chris Weidman on Friday pulled out of his UFC 184 fight against Vitor Belfort on Feb. 28 at Staples Center because of a rib injury he sustained this week while training.
Ronda Rousey's fifth women's bantamweight title defense, against No. 1-ranked challenger Cat Zingano, has been elevated to the main event.
The unbeaten Weidman (12-0) underwent a medical exam following the rib injury that established he couldn't defend his title.
A UFC spokesman said there is no timetable for Weidman's return.
Weidman suffered a training-camp knee injury last year after defeating former longtime middleweight champion Anderson Silva in December 2013.
Venice's Rousey anchored a UFC card in her debut, beating Liz Carmouche at Honda Center.
She'll be joined on the card by another contender, Holly Holm, a former kickboxing champion who'll make her UFC debut in the new co-main event against Raquel Pennington.
