The Middlesbrough midfielder Julio Arca could be out of action until December after scans confirmed medial ligament damage.
The news that the 26-year-old Argentine is facing at least two months on the sidelines with the knee problem he suffered against former club Sunderland on Saturday will come as a blow to Gareth Southgate.
The Boro manager was at least able to comfort himself with the news that strikers Tuncay Sanli and Mido could play against next weekend after tests on their respective injuries revealed no lasting damage.
Southgate said: "Both Mido and Tuncay have gone for scans and there's no significant damage, and both have a chance of playing on Sunday.
"However, the injury to Julio looks more serious. It's the medial ligament in his knee and it looks like it will be at least two months."
Arca hobbled off the field after extensive treatment 25 minutes into Saturday's 2-2 Premier League draw, but then had to be carried on a stretcher to the dressing room. Southgate later admitted that he feared medial ligament damage straight away.
The manager at least knows he has cover in that position, with captain George Boateng, who has played much of his football this season wide on the right rather than in his favoured central position, starting on the bench at the weekend to accommodate new signing Gary O'Neil.Reuse content