The 26-year-old has firmly established himself as one of the best goalkeepers in the world during his six year stay at Old Trafford, but has repeatedly flirted with the idea of a move back to Madrid, having started his career at La Liga giants Atlético.
Real Madrid are eager to sign a world-class goalkeeper ahead of the 2017/18 season, especially given the number of high-profile mistakes made by Keylor Navas this season.
And a number of Spanish newspapers, including Marca and Don Balon, have suggested Real will once again test United’s resolve by bidding around £60m for the Spanish international.
Should Real be successful in tempting De Gea away from Old Trafford, there are a number of players Jose Mourinho could turn to as a replacement.
There is a strong possibility of Real offering Navas in part-exchange for De Gea, similar to the offer they made in 2015. But with the Costa Rican’s pedigree dropping in the last two seasons, it remains to be seen whether Mourinho would be open to such an offer.
Signing a goalkeeper from a Premier League rival would involve paying a premium, although United have long had an interest in Tottenham’s captain Hugo Lloris, and the Old Trafford hierarchy will have been buoyed by comments made by the Frenchman last week.
“I feel good at Tottenham, but in football everything's fragile and can change. Some things you can't refuse,” he told Le Figaro.
Leicester’s Kasper Schmeichel and Stoke City’s Jack Butland are other options closer to home that United may well turn to.
Click through the gallery above to see the goalkeepers Jose Mourinho may consider to replace David de Gea.