McManus was substituted during the win over Palace with Mowbray sounding pessimistic by the news of his captain’s injury.
“It’s not good news,” the Boro boss admitted looking ahead to tomorrow’s trip to Scunthorpe. “Stephen had a scan this morning and it’s came back that he has some ligament damage and he’s looking at a period out.
“He went over on his ankle and twisted it. I could see him wincing every time that he played the ball so he every bit the heroic skipper because he’s been brave enough to carry on playing but it was the right decision to take him off.”
Barry Robson is also likely to miss the trip to Scunthorpe due to a thigh strain.