The heavily anticipated UFC middleweight title fight between champ Chris Weidman and top challenger Vitor Belfort is off.

MMAjunkie has learned from several sources close to the promotion that Weidman has suffered an injury in training and has been forced to withdraw from the contest. The sources all spoke on the condition of anonymity because they were not authorized to publicly discuss the matter.

An announcement from the organization is expected shortly.

The contest was expected to headline next month’s UFC 184 event, but that honor will now fall to UFC women’s bantamweight champion Ronda Rousey, who faces Cat Zingano in what was originally announced as the co-main event.

UFC 184 takes place Feb. 28 at Los Angeles’ Staples Center. The main card airs on pay-per-view following prelims on FOX Sports 1 and UFC Fight Pass.

The nature of Weidman’s injury wasn’t immediately known, nor was a timetable established for his return.

Weidman and Belfort originally were set to meet in May at UFC 173 before Belfort was pulled from the card in the wake of the Nevada State Athletic Commission’s ban on testosterone-replacement therapy, of which Belfort was a multi-year participant. Weidman went on to fight Lyoto Machida and earned a unanimous decision.

The UFC moved then Weidman vs. Belfort to Feb. 28 in Los Angeles.

Rousey and Zingano were originally expected to face each other in 2013 after serving as coaches on “The Ultimate Fighter 18.” However, Zingano blew her ACL and was forced to withdraw from the opportunity. Zingano re-earned her title shot with a third-round TKO of Amanda Nunes at UFC 178.

Rousey, meanwhile, defended her belt a fourth time this past July with a 16-second stoppage of Alexis Davis at UFC 175. In lieu of Zingano’s injury, she coached “TUF 18″ opposite rival Miesha Tate and earned a third-round submission.

The UFC 184 lineup currently includes:

Champ Ronda Rousey vs. Cat Zingano – for women’s bantamweight title Jake Ellenberger vs. Josh Koscheck Holly Holm vs. Raquel Pennington Tony Ferguson vs. Yancy Medeiros Roan Carneiro vs. Mark Munoz Alan Jouban vs. Richard Walsh Roman Salazar vs. Norifumi Yamamoto Derrick Lewis vs. Ruan Potts James Krause vs. Valmir Lazaro Dhiego Lima vs. Tim Means Masio Fullen vs. Alexander Torres

For more on UFC 184, check out the UFC Rumors section of the site.