"I'm so unbelievably disappointed that this happened," Velasquez said.

UFC heavyweight champion Cain Velasquez has unfortunately injured his right knee in training, forcing himself for the title defense against Fabricio Werdum on November 15^th.

Velasquez (13-1) was the pride and joy of the UFC's first card in Mexico City; marking a 21,000-seat arena sold out in just about eight hours. The Mexican-American champion has a huge fan following in a growing MMA market.

He stated: "To say I was looking forward to fighting in Mexico for the first time is an understatement. I wanted to fight on that card so bad."

His injury problems have run down the promotion of one of its biggest attractions even though Velasquez is hailed as one of the UFC's most talented fighters.

Velasquez's injury gave a shot for the 40-year-old Hunt (10-8-1). He banged Roy Nelson in Japan on September 20^th for his fifth win in seven fights. The New Zealander has only three weeks to prepare for a high-altitude fight.

Mark Hunt will step in to meet his opponent, Werdum, for an interim heavyweight title at UFC 180. It is the mixed martial arts promotion's debut in Mexico.

Hunt declared he is thinking to begin his training soon that is why he is planning to fly to Mexico on Wednesday.

"I feel blessed to have this opportunity to fight for another world title," Hunt said. "This is something that doesn't happen often to people."

Werdum (18-5-1), on the other side of the box, is a 37-year-old Brazilian veteran based in Los Angeles. He has victor seven of his last eight fights and has been training hard in Mexico for nearly two months to adjust to the altitude.

Random reports showed that six of the UFC's nine reigning champions had injury problems in the past year. Jon Jones, Chris Weidman, Anthony Pettis and Jose Aldo have been obliged to postpone title defenses because of injuries, as welterweight champion Johny Hendricks tore his biceps in a title defense.

 (Source: Yahoo Sports)