Cotterill: "He kept saying he was all right, but I could see he couldn't move properly. He wasn't in too much pain at the time because it was a two-thirds rupture and probably because of his strong thighs.
"It's a major, major blow for Kris and the club. My heart goes out to the lad at a time like this. It's something he simply has to get his head round.
"He started the season like a train and we know lots of clubs have been watching him. He's still got a fantastic future ahead of him, it's just that it's on hold for the moment."
Kris played the key pass for Andy Cooke to score his winning goal against Ipswich and also scored himself with some terrific play to salvage a point against Norwich.
Commons will have an arthoscope on the knee this week which should confirm the scan's findings before he is then be given a timetable for treatment and recovery.