Nathaniel Clyne
Nathaniel Clyne has been in excellent form this seasonReuters

Manchester United boss Louis van Gaal has reportedly stepped up his efforts to sign Southampton's Nathaniel Clyne after failing in his efforts to sign Barcelona's Dani Alves.

The Dutchman has been forced to deploy Antonio Valencia as a makeshift right-back due to the below par performances of Rafael da Silva this season.

Now with the Brazilian expected to leave Old Trafford this summer, the Red Devils are reportedly on the hunt for a new right-back as Van Gaal looks to strengthen his back-line and launch a fresh attack on the Premier League title next season.

Alves, who is out of contract this summer, was believed to be United's primary target this summer, but van Gaal has been forced to look at other alternatives after Barcelona chairman Josep Maria Bartomeu recently hinted that the Brazilian may be extending his stay at the Nou Camp.

"He is an important player who contributes a lot," said the Spaniard, according to the Daily Star. "I hope he renews. We have asked him to and we're discussing it. I know he'd like to stay and Barca want him to stay."

As a result, United have reportedly quickened their efforts to sign Southampton's Clyne, according to the Daily Star.

The former Crystal Palace defender has been one of the main reasons behind the Saints' excellent run in the Premier League this season, forming a formidable partnership with left-back Ryan Bertrand.

Although the Red Devils have been linked with a move for Clyne throughout this reason, they haven't been really serious on landing the 24-year-old.

However, following reports of Alves' snub, United have reportedly made signing Clyne their top priority this season.

It is believed that the Red Devils, who were able to prize away Luke Shaw from the Saint Mary's for a reported £30 million last summer, will be making an initial bid of £20 million to land Clyne.

However, United will not be able to secure his signature as Premier League leaders Chelsea are also believed to be interested in the 24-year-old.