De Gea, 28, has been stalling on signing a new deal at Old Trafford in the knowledge that a bumper £300,000-a-week is on offer at PSG, who could get round any Financial Fair Play restrictions by selling Neymar to Real Madrid and building their team exclusively around Kylian Mbappe.
The Spain international could be set to earn around £15.5m a year in wages with the French giants, taking his potential salary to over £60m if he were to sign a four-year deal in Paris.Losing a player of De Gea's quality would be a huge blow to United and to manager Jose Mourinho, whose side produced yet another underwhelming performance as they were held to a goalless draw by Crystal Palace at Old Trafford which leaves them seventh in the Premier League table.
De Gea is regarded as one of the best goalkeepers in the world, recovering from a shaky start when he joined United in 2011 to win the Premier League, FA Cup, League Cup and Europa League.
A dream move to Real Madrid fell through on transfer deadline day in 2015, and that prospect ended when Thibaut Courtois joined the Champions League holders from Chelsea last summer.
United have been keen to tie De Gea down for the long-term future but they have been left frustrated in negotiations, with Mourinho recently admitting he was 'not confident' of being able to keep him.
With Juventus happy with their keeper Wojciech Szczesny, PSG are now the clear front runners and able to sign a pre-contract agreement with United's No 1 in January.
PSG signed Italian legend Gianluigi Buffon from Juventus last summer but the plan was only to have the 40-year-old as first-choice for one season.
The French club have the most dazzling attack in world football with a front three of Neymar, Mbappe and Edinson Cavani, but they face Champions League exit if they are beaten by Liverpool in Paris next week and there is a feeling they have to improve the balance between defence and attack.United are already looking at a number of goalkeepers who could replace De Gea with England's No 1 Jordan Pickford of interest.
Mourinho was seething after Saturday's draw, saying: 'We played as if it was just one more game, not a game we really needed to win.
'We found the space very well by analysing the opponent and by training, but there was not enough intensity, not enough desire. My feeling is it wasn't enough from the heart.'