Jasper Cillessen
Cillessen has received no formal approach from UnitedGetty

Ajax manager Frank de Boer has revaled that it will be difficult for Jasper Cillessen to reject a move to Manchester United if they come in with a hefty bid for the player, promising a massive wage hike on his current contract.

The Mirror reports that United have made the Dutch number one their top priority for the summer, should David de Gea leave the club this summer in favour of a move to Real Madrid.

Louis van Gaal has worked with the 26-year-old during his time with the Netherlands first team in the 2014 World Cup where he put in a glorious performance to take the Dutchmen on their way to the semifinals, where they were defeated by Argentina.

Meanwhile, the BBC reports that any move for De Gea to Madrid would have to include Sergio Ramos in an exchange to Old Trafford, something the Spanish club have refused to comply with thus far.

"For us, it would be a disaster if that's going to happen because it's already very difficult to find a good goalkeeper, especially if you have the best goalkeeper in Holland," de Boer told Sky Sports News.

"We want to keep him and he wants to stay but, if Manchester United come with a bag of money, it can be difficult.

"We have to wait, but the transfer period still has a long way to go," he added.

United have been very active thus far in the window, signing four players, namely Matteo Darmian from Torinio, Morgan Schneiderlin from Southampton, Memphis Depay from PSV Eindoven and Bastian Schweinsteiger from Bayern Munich.

The Red Devils are also in the market for a defender and a striker, with the club keeping a close tab on Valencia defender Nicolas Otamendi amid the uncertainty over the transfer of Ramos, according to the Guardian.