Jim Harbaugh has no doubt star inside linebacker NaVorro Bowman will regain his top-notch ability following rehab from a torn ACL in his left knee.

But the San Francisco 49ers coach has no idea when Bowman will return. Harbaugh said Tuesday that Bowman, one of the most dominant defensive players in the league, has a "grueling rehab" ahead of him.

According to Harbaugh, the Niners are not sure if Bowman, 25, tore his MCL as well, and physicians will have to wait two to three weeks to decide when to repair his ACL.

A source previously told ESPN NFL Insider Adam Schefter an MRI exam revealed that Bowman suffered a torn ACL and MCL, although the MCL is expected to heal on its own.

The team hopes that Bowman, who suffered the injury in Sunday's NFC Championship Game against the Seattle Seahawks, will be ready to play again by September, but Harbaugh said there is no way to tell at this point when he will return. Harbaugh did say, however, that the team expects Bowman to play in 2014.

"He's got healing ahead," Harbaugh said Tuesday. "He's got grueling rehab ahead. That is not the way that you would've wanted or foreseen his offseason to be after coming off what many have talked about -- and deservedly so -- of a defensive-player-of-the-year type of performance. Great year by NaVorro.