Boss David Moyes is currently without as many as 12 senior professionals for the visit to West Brom in the Premier League this weekend.
"Jack had a medial ligament injury," Moyes explained.
"He was scanned on Monday after getting it in the game on Saturday, and the scan has not come up with anything. I'm hoping that it shouldn't keep Jack out too long.
"He's just beginning to get a couple of games under his belt. To have Jack out (against Burnley) was a blow.
"They thought that he'd opened his medial ligament so the scan has not shown a great deal. We're hopeful that he might just have to stay off it for a week or so and let's see how he is."