OWINGS MILLS, Md. -- In a situation that is starting to feel reminiscent to last season, the Baltimore Ravens are uncertain when wide receiver Breshad Perriman will return.

Asked if there was any update on Perriman, coach John Harbaugh said Tuesday, "I don't. I wish I did."

Harbaugh was told Perriman would return by the middle of August after the 2015 first-round pick partially tore the ACL in his left knee two months ago. But, at this point, Baltimore doesn't have a time frame on when Perriman will get back on the field.

"I haven't been told when he's going to back to practice," Harbaugh said. "I'm just like the fans. I'm waiting for him to get back out there. When he's ready, he'll be back out there."

Perriman, who is on the physically unable to perform list, is running, according to Harbaugh. He injured his left knee in a non-contact drill on June 9.

Breshad Perriman lost his entire rookie season to injury. Tommy Gilligan/USA TODAY Sports

The Ravens have until Sept. 3 to determine whether to keep Perriman on PUP. If he remains on the list, he would miss at least the first six weeks of the regular season.

This isn't the first time Perriman has dealt with a long recovery. He missed his entire rookie season after injuring his right knee on the first day of training camp.

"It would definitely be nice to get him out here at some point," quarterback Joe Flacco said. "But, at the same time, you can't bring him back too early because he's not ready."