A welterweight grudge match between Anthony Johnson (8-3 MMA, 5-3 UFC) and John Howard (13-4 MMA, 3-0 UFC) has been put on indefinite hold as "Rumble" was forced to bow out of the contest due to a knee injury.

The pair was scheduled to meet on the main card of "UFC on Versus 1: Vera vs. Jones," which takes place March 21 in Broomfield, Colo.

The injury was first reported by ProMMANow.com and has subsequently been verified by multiple outlets.

The UFC has yet to officially announce Johnson's withdrawal or a replacement opponent, who would be taking the fight on five-weeks' notice.

The potential for a Howard-Johnson matchup first surfaced in early 2009, but "Doomsday's" camp reportedly turned down the fight in favor of waiting for their fighter to develop further before taking on such a highly ranked opponent. Johnson has publicly bashed Howard ever since because of that decision.

"[Howard] said it was his management's call that made him not accept the fight," Johnson told MMAjunkie.com back in April 2009. "But at the end of the day, it's really your call. You're the one fighting. You're the one that's got to go out there and do the damn thing, not your management."

Howard has yet to comment on Johnson's withdrawal, and representatives of his camp were not immediately available for comment.

Howard, a one-time IFL fighter who also competed for the New Jersey-based Ring of Combat promotion, owns a six-fight win streak, and he's a perfect 3-0 in the UFC. In addition to split-decision wins over Chris Wilson and Tamdan McCrory, Howard also recently scored a come-from-behind third-round knockout of Dennis Hallman at The Ultimate Fighter 10 Finale.

Howard, who had lost the first two rounds of the December fight and seemed on his way to a unanimous-decision loss, scored the fight-ending left punch with just five seconds remaining in the final round.