David De Gea first burst onto the scene during his time at Atletico Madrid where he won both the UEFA Europa League and the Europa Super Cup. At the time, United was struggling to find a replacement for Edwin van der Sar, which made Sir Alex waste no time in getting the services of the Spaniard.
De Gea struggled in his initial days at Old Trafford, as he took some time to adjust to Premier League football, but once he did, there was no looking back. David has won almost everything at United, which includes the Premier League and the UEFA Europa League.
He was even named Sir Matt Busby Player of the Year for 3 consecutive seasons, which is a record in Manchester United's history.
However, recent results haven't been great for the Red Devils, with their talismanic goalkeeper reportedly reluctant to sign a new deal. It's believed that De Gea doesn't think the team is good enough to win significant silverware anytime soon. The Spain international is at the peak of his career, and the only way he would be among the best is by winning trophies such as the Champions League.
If David leaves next summer, it would be a big hole to fill for any new keeper coming in. Though there are world-class goalkeepers around, not many are at De Gea's calibre. Here is a look at the possible replacements for the Spaniard if he decides to leave Manchester United next summer.
#3 Gianluigi Donnarumma (AC Milan)
Gianluigi Donnarumma has drawn interest from many top European clubs since bursting onto the scene at the San Siro as a mercurial talent tipped for the very top. He is AC Milan's #1 goalkeeper, and they are trying hard to reclaim their old glory days, but are yet to succeed in that regard.
If David De Gea decides to leave, then a United move for Donnarumma wouldn't seem too far-fetched, especially when considering the goalkeeper shares an agent - Mino Raiola, with the likes of Paul Pogba and Henrikh Mkhitaryan, previously coming to Manchester United from their respective clubs.