Manchester United midfielder Owen Hargreaves is facing five weeks on the sidelines with a hamstring injury.
The 29-year-old, returning from long-running knee problems, made his first start in two years last weekend but limped off after just six minutes of the 2-1 victory over Wolves.
United boss Sir Alex Ferguson admitted he had taken a gamble in naming Hargreaves in his starting XI, describing the decision as a “disaster”.
And Ferguson has now confirmed the player will now miss Wednesday night’s Manchester derby and will be out until December with his latest injury problem.
He said: “We were at the stage where we knew Owen’s knee was OK.
“His training performances for eight or nine days previously had been terrific. He had done really well, which is why we took the chance.
“But maybe the tension in the build-up for the lad was too much and he suffered because of it.”