Manchester United are concerned that Real Madrid will only sell Gareth Bale if they get David de Gea in return, according to reports.
United have long been linked with a move for Bale, and Ed Woodward is reportedly more optimistic of finally landing the Welsh winger next summer than at any previous point.
However, The Mirror claims that Madrid may demand De Gea to move to the Bernabeu as part of any deal which would take Bale in the opposite direction, leaving Jose Mourinho with a dilemma.
Madrid are understood to have a long-standing interest in De Gea and came close to signing him in 2015, only for an admin error to scupper the deal at the 11th hour.
United are reluctant to lose the Spaniard, although De Gea himself is reportedly eager to play for Madrid at some stage in his career and would be open to a move next summer.
Bale, meanwhile, has been limited to just four La Liga starts so far this season, scoring two goals.