"I tried to ignore the pain until now, thinking I had just sprained the knee," he said. "I kept training without using my legs. I wanted to get to the fight in a good condition somehow, but the MRI diagnosed that I broke my ligaments, and now I can't fight!
"I apologize to all my supporters. Please remember that I am a fighter and that I want to fight for all my life. But now, I must wait until I am fully healed before I can fight again. I hope you all understand."
This marks the third time in a row that a scheduled fight between Sakara and Rivera has been canceled.
First, a proposed UFC 118 fight was scrapped after Rivera pulled out due to a broken arm. Then Sakara was forced to withdraw just hours before their UFC 122bout after succumbing to flu-like symptoms. And on Monday, Rivera informed The MMA Hour audience that a Sakara knee injury had once again called off the fight.
"I thought it was a joke," Rivera said. "I couldn't believe it."
As a result, Rivera will now face Costantinos Philippou on the UFC 133 pay-per-view card.
Sakara (15-8, 1 NC) is coming off a loss to Chris Weidman in March. Prior to that defeat, the 29-year-old Italian had won three in a row. No word on how long he will be sidelined for due to the knee injury.
UFC 133, headlined by Rashad Evans vs. Tito Ortiz, airs live on pay-per-view on Aug. 6 from Wells Fargo Center in Philadelphia.