Manchester United are reportedly free to sign Gareth Bale in summer with reports said Real Madrid are happy to let the Wales international depart.
Bale was close to joining Manchester United four years ago, only for the 28-year-old to move to Spain to Real Madrid instead.
Bale has won the Champions League three times since his transfer from Tottenham, as he starring under Carlo Ancelotti, Rafa Benitez and Zinedine Zidane.
The European champions have De Gea among their top targets for next summer, along with another former Atletico Madrid goalie Thibaut Courtois.
And Mourinho could be tempted to let De Gea go if it means receiving Bale in return.
Meanwhile, the former United manager David Moyes confirmed that the former Tottenham star was among his top targets alongside with Chelsea playmaker Cesc Fabregas, when he took over from Sir Alex Ferguson in summer of 2013.