UFC heavyweight champion Cain Velasquez (9-0) is resting comfortably in a Las Vegas hospital following surgery Thursday morning to fix a 90-percent tear of his right rotator cuff.
Velasquez, 28, said he injured the shoulder during his UFC title- winning fight against Brock Lesnar last October.
Under the care of Dr. Steven Sanders, Velasquez's "surgery went well,"
said the fighter's trainer, Javier Mendez.
UFC president Dana White says the recovery is likely to keep Velasquez out of the octagon until at least September.
"He's doing great, actually," White said. "They were saying the recovery time is usually eight months, and hopefully he can do it a little quicker than that, but we'll see."
"Surgery went well," Velasquez tweeted on Monday. "Back at Joe Grasso's lifting legs. Best place to train."
The undefeated heavyweight expects to learn the specifics of his rehabilitation program on Friday. Based on what doctors told Mendez, the American Kickboxing Academy chief believes Velasquez, who fights out of San Jose, Calif., would be ready to compete by August.
As a result of the injury, UFC officials booked a fight between No. 1- contender Junior dos Santos (12-1) and Lesnar (5-2) for June. The winner will earn a guaranteed shot against Velasquez later in the year
-- making a September or October return most likely for the champion, Mendez said.
Should the 33-year-old Lesnar rebound with a win, a second bout against Velasquez would generate a blockbuster pay-per-view event.
Meanwhile, dos Santos, 26, would affirm his status as the No. 1 contender in UFC's heavyweight division with a victory over the powerhouse wrestler.
"I love the fight," Mendez said. "Either way, it makes the best of a bad situation for Cain."
Josh Gross covers mixed martial arts for ESPN.com. Information from The Associated Press was used in this report.