De Gea would be Manchester United's best summer signing - Phil Neville

Committing David De Gea to a new long-term contract is the best bit of business Manchester United could seal this summer, according to Phil Neville.

The Spaniard has improved significantly in every season since arriving at Old Trafford in a £17.8 million (€24.7m) deal from Atletico Madrid in 2011 and a series of outstanding individual displays earned him a place on the PFA's six-man Player of the Year shortlist.

Real Madrid are avowed admirers of De Gea, who will enter the final year of his United contract this summer, and Neville believes keeping the 24-year-old is crucial to the club's hopes of challenging for the Premier League title next season.

"The biggest thing is David De Gea, and keeping him at the football club," the former Red Devils defender replied when asked about United's potential transfer business.

"From when he first came, to how he is now, I don’t think I’ve seen a player develop and improve as quickly as him.

"He's now at the stage where you’d say he’s world-class. He’s winning football games on his own. It’s a flippant thing to say but he really is.

"Last minutes saves against Everton, Hull, Arsenal away - there’s seven or eight occasions where he has won United games which just shows you that he is world-class."