Baltimore Ravens head coach John Harbaugh has conceded that he is unsure whether wide receiver Breshad Perriman will be fit to play in his side's season opener.

The Ravens selected the 21-year-old in the first round of the 2015 Draft, but he has been unable to train for the past month after sustaining a knee injury on the first day of training camp.

Harbaugh admitted that Perriman was not completely ruled out for the game, but could not reveal that he would be available to play.

"I don't know. I really don't have the answer for that," Harbaugh told reporters. "I think he has a chance, yes. But whether it's to what degree, that's wide open right now. I don't know."

The Ravens open their season against the Denver Broncos on Sunday.