Heavy speculation that UFC heavyweight champion Cain Velasquez (9-0 MMA, 7-0 UFC) would make his first title defense against Junior Dos Santos in Toronto came to naught today with news that Velasquez is on the bench with an injury.

American Kickboxing Academy trainer Javier Mendez today told MMAjunkie.com (www.mmajunkie.com) that the champ injured his right shoulder during a winning bid for Brock Lesnar's title at UFC 121, though he declined to disclose it at the time because the severity of the injury was unknown after an initial MRI.

When a second MRI this past week revealed a badly torn rotator cuff which could bench Velasquez for a minimum of 4-6 months – if not longer – a defense in April became unrealistic.

News of the injury was first reported today by MMAFighting.com, who confirmed the injury with UFC president Dana White.

Although disappointed, Velasquez is optimistic about his recovery and wants to undergo surgery as soon as possible, Mendez said. Velasquez's rotator cuff is 90 percent torn and will need extensive physical therapy.

"That's the fight game," the trainer said. "You've got to expect that in this trade."

The UFC was made aware of the injury following UFC 121 and put the brakes on a Velasquez vs. Dos Santos showdown. Dos Santos manager Ed Soares could not be reached for comment on the injury development, and it's unknown at this time whether the UFC will forge ahead with another bout for the challenger.

An interim title situation would also seem premature at this point. White anticipated Velasquez would return in summer 2011.

Mendez, however, thinks that timeline might be a bit too charitable.

"They say the rehab on that type of injury is going to take anywhere from 4-6 months," he said. "Then from there he's got to get fight-ready."

So for now, the top of the heavyweight division is in flux. Meanwhile, a welterweight title match between reigning champ Georges St-Pierre and challenger Jake Shields could headline the UFC's first trip to Toronto, possibly UFC 129, in April at the Rogers Centre.

Unbeaten inside the octagon, Velasquez stormed his way to a title shot with six consecutive victories and took the belt from Lesnar with a first-round beatdown.