Manchester United are closing in on completing a deal in signing Valencia defender Nicolas Otamendi, according to the Argentinean publication Diario Ole.

The 27-year-old has already signed a preliminary contract with the Red Devils in order to make a switch to Old Trafford in the summer. The two clubs are yet to reach an agreement as the final fee has still not been decided.

The Argentine international was signed from FC Porto in February 2014 and was sent on loan to Brazil's Atletico Mineiro for the rest of the season. He has been a star player in his debut season in the La Liga as he has featured in 34 league appearances.

Otamendi played a key role in helping his side sit in fourth spot and they are one win away from returning to next season's Champions League. After the end of this term, he will join his national team for the 2015 Copa America, starting 11 June in Chile.

The tough tackling and pacey centre-back defender is keen on joining Louis van Gaal's side as the Dutchman looks to bolster his back four for the next season. He has a €50m (£36m, $55.7m) release clause in his contract.

United are looking to reduce the fee as they are not considering paying the Spanish club's asking price. However, Valencia want the release clause to be paid in order to part ways with the player, despite their interest in retaining the player.

The Copa America will end on 4 July and the deal is likely to be announced after the South American championship as Otamendi does not want his club future to distract his performance for Argentina.

Meanwhile, United are willing to allow their defender Jonny Evans leave Old Trafford this summer. The Northern Irishman is attracting interest from Everton as Roberto Martinez is preparing a £10m ($15.5m) bid to land him. Evans has one year left on his contract with his current employers.

Otamendi could replace Evans at United and also be a regular inclusion in the Red Devils' defence for next season.