Baltimore Ravens running back Keaton Mitchell suffered a full tear of the ACL in his left knee on Sunday night, a source told ESPN's Jeremy Fowler on Monday.
There is optimism that Mitchell will make a full recovery, the source told Fowler.
At his Monday media session, Ravens coach John Harbaugh confirmed there was ligament tear with Mitchell but wouldn't confirm the specific nature of the injury.
"It's a long-term knee thing," Harbaugh said. "There wasn't cartilage-type damage and things like that, so that helps quite a bit. It'd be a little cleaner and he'll go to work. I'm sure he'll be here every single day with the team and doing his part to get back."
Mitchell, an undrafted rookie, sustained the injury in the fourth quarter of the Ravens' 23-7 victory over the Jacksonville Jaguars when he was tripped up by safety Andrew Wingard, causing his left leg to bend awkwardly after he landed on it.
This is the third significant player the Baltimore offense has lost. Starting running back J.K. Dobbins sustained a season-ending Achilles injury in the season opener, and tight end Mark Andrews will miss at least the rest of the regular season after injuring his ankle in Week 11.
Now, the Ravens will be without Mitchell, who started Sunday and totaled 73 yards on nine carries (8.1-yard average) before the injury. Mitchell has 396 yards on 47 carries this season (8.4-yard average) and two rushing touchdowns.
With Mitchell out, the NFL's No. 1 rushing attack will rely on Gus Edwards and Justice Hill. Baltimore will promote two-time Pro Bowl running back Melvin Gordon from the practice squad to fill Mitchell's spot on the 53-man roster, according to Harbaugh.
"He's been working super hard," Harbaugh said Sunday night of Gordon. "He's in great shape, and he'll be ready to go."
ESPN's Jamison Hensley contributed to this report.