Sir Alex Ferguson is confident Rio Ferdinand will not be consigned to a lengthy period on the sidelines after identifying the root of his current injury problems.
Ferdinand has missed the last couple of weeks' action with Manchester United after picking up what was thought to be a calf injury.
However, it has now been confirmed the injury relates to a previous problem with his lower back.
The England defender will not be fit for tomorrow's Barclays Premier League encounter with Everton at Old Trafford, but the 31-year-old should be back in action soon.
"It is back related," Ferguson said. "We are not putting a timescale on it but it is not a situation where we are saying it will be months, it might be a couple of weeks or it might be a few weeks but that is it."
With Ferdinand out, Ferguson is relieved to have Nemanja Vidic available after he missed the defeat at Chelsea immediately before the international break with a calf problem.
However, Gary Neville is suspended and John O'Shea is almost certain to miss out with a thigh injury picked up in the Republic of Ireland's controversial World Cup exit in France on Wednesday.
Northern Ireland international Jonny Evans is a doubt as well, leaving Ferguson with some "patching up" to do in defence.