The two sides are currently negotiating a deal for Romelu Lukaku to move to Italy, with the Argentine forward reportedly coming the other way.
However, the Daily Mail claim Dybala is unwilling to move to Old Trafford and is waiting to speak to new boss Maurizio Sarri about his future.
The report claims United are growing impatient waiting for the 25-year-old, meaning they will turn their attention to Costa.
But in another fresh twist for the Red Devils, the Brazil international is also said to be reluctant to make the move to England.
Costa nearly moved to United 12 months ago as Jose Mourinho intensified his search for a left winger, with the star-billing the club can offer him said to be a potentially decisive factor.
Click Here: cheap kanken backpack