A calf injury has forced the postponement of Pat Curran vs. Patricio “Pitbull” Freire for the Bellator featherweight, officials announced Wednesday night. The bout was to serve as the main event for the June 6 show on Spike TV.

Curran won the belt from Daniel Straus, and was set to meet Pitbull, who won the Season 9 featherweight tournament title. Bellator is expected to announce the complete card at a future date.

“I’ve been training incredibly hard for this fight by pushing myself to my absolute limits in training,” Curran said. “Unfortunately during some conditioning drills, I suffered a bad calf strain that has halted my training for one of the biggest fights of my career. I have my sights set on getting back into the cage as soon as possible with July in mind, but I want to be 100-percent healthy heading into that cage to smash Pitbull.”

Curran (20-5) re-claimed the title in March when he scored a fifth round submission victory over Daniel Straus. Last November, Straus defeated Curran via decision, but officials went ahead with Curran-Pitbull instead of booking a third meeting with Straus.

Freire (21-2) has won four straight since a 2013 split decision loss to Curran for the featherweight title. His current run includes finishes of Justin Wilcox, Diego Nunes and Jared Downing.