Jose Mourinho will be handed a blow in his pursuit of Manchester City in the title race with the need to sell before any purchases can be made in January.
Manchester United have found themselves eight points behind their rivals after Chelsea handed them defeat last weekend.
The Red Devils walked away from a late move for Ivan Perisic towards the end of the summer and any possibility of reigniting interest will hinge on sales.
Mourinho has spent a £285million since moving to Old Trafford and the Portuguese's hopes of bolstering his squad to cope with European commitments have now been dashed, report the BBC.
Luke Shaw will likely be sacrificed, though his price will be modest compared to the £27m that United splashed out on the former Saints star in 2014.
Marouane Fellaini remains a favourite of Mourinho's, but a starring role in the build-up to the World Cup could push him to make a move
United host Newcastle after the international break before Champions League action with Basel.