United have seen Anthony Martial misfire this season.
Though he’s currently injured, the France international had scored just seven goals before being sidelined in March.
And there’s a sense Martial may never fulfil his potential at Old Trafford, despite the obvious talent he possesses.
Dortmund will need a top attacking player to fill the void left behind by any possible Sancho departure.
They wanted Martial when it looked as though he could leave during Jose Mourinho’s reign and, therefore, including him in a swap deal would certainly be logistical.