Seth Mitchell-Johnathon Banks off

On Wednesday, Golden Boy Promotions announced that top American heavyweight prospect Seth Mitchell would face Johnathon Banks on July 14 in the HBO co-feature of the Amir Khan-Danny Garcia main event.

On Thursday, Mitchell-Banks was canceled.

Mitchell, who had been secretly training with an injured right hand, was advised to rest the hand for 6 to 8 weeks after seeing the doctor for an injury that he suffered in his knockout win against Chazz Witherspoon on April 28.

Golden Boy chief executive Richard Schaefer told ESPN.com that he had received a copy of the doctor's report and that the fight was "definitely off."

"He injured his right hand in his last fight, which was five weeks ago, but he thought the (injury) would go away," Schaefer said. "He went to see the doctor and the doctor said that nothing is broken but he recommended that Seth not do any sparring or have any contact for the next 6 to 8 weeks. He is scheduled to see a hand specialist next week and he will be evaluated to see if anything additional needs to be done."

Schaefer said the doctor's report indicated that Mitchell had "sprains and strains" in his right wrist and hand and that his hand should be placed in a split.

"If the doctor says the hand needs to be in splint, obviously there is not going to be a fight," Schaefer said. "You want to make sure he takes care of the injuries and comes back when he's ready. So I informed HBO about what is going on and we will see what the best way is to replace the fight and take it from there. We have a very good stable of fighters and we will come up with a fight worthy of an HBO 'World Championship Boxing' opening bout for July 14."

Given how hard-hitting Mitchell's fight against Witherspoon was, it's no wonder he hurt his hand. Witherspoon badly hurt Mitchell (25-0, 19 KOs), a former Michigan State linebacker from Brandywine, Md., in the first round of the bout, which was the co-feature on the card headlined by the Chad Dawson-Bernard Hopkins light heavyweight championship rematch. But Mitchell, who turned 30 on Tuesday, came storming back to score a third-round knockout in a slugfest in which they traded heavy punches.

Banks (28-1-1, 18 KOs), 29, of Detroit, is a former cruiserweight title challenger who has been fighting as a heavyweight since 2009, and has gone 8-0-1. He figured to be a test for Mitchell, who has been prominently mentioned as a future possible opponent for heavyweight champion brothers Wladimir and Vitali Klitschko, whose K2 Promotions handles Banks.

"This fight was a great opportunity for Seth in his progress, but our plan remains to get him, within the next 12 months or so, a heavyweight title shot. This is a setback, but it happened. It's disappointing for the fans, for us and certainly for Seth Mitchell. But I think it is a momentary setback and as soon as he's cleared to fight he'll be back on TV."

Earlier Thursday, Sharif Salim, Mitchell's manager, denied there was any serious issue with Mitchell's hand when asked about it by ESPN.com.

"We're in camp and we're moving forward," he said. "Seth fights through a lot of things. There are always bumps and bruises from the last fight, but we are preparing for the fight on July 14. We're not here to talk about injuries or make excuses."