Sporting open to sale of Carvalho.Getty

Sporting Lisbon will have no problem selling William Carvalho to Manchester United – as long as the Premier League side pay his £37m release clause in full.

United's interest in the 22-year-old has been revived over the last week with the club sending representatives to the Portuguese capital on Sunday to negotiate a deal for the powerful midfielder, reports in the Portuguese press suggested.

Following Portugal's dismal World Cup campaign that was brought to an end at the group stages, Carvalho admitted he could leave Sporting despite claiming he intended to honour his contract earlier in the summer.

United have added Spaniard Ander Herrera to their midfield already this summer but if they wish to partner him with Portugal international Carvalho then they must be prepared to meet Sporting's terms.

"It's not like the old days when players left Sporting at any price," the club's sporting director Augusto Inacio told their TV channel, the Mirror report.

"We are not concerned with William Carvalho because we have alternatives, who will want to play as well. The termination clause ensures a great deal to Sporting. I am very pleased with the negotiations."

Carvalho started just one game for Portugal during their campaign in Brazil but that decision has been widely recognised as a grave error made by under fire manager Paulo Bento. After his breakout campaign last term he was handed the club's Player of the Year award having scooped the monthly accolade on four occasions during the 2013/14 season.

With Chelsea and Monaco, where his former manager Leonardo Jardim took charge earlier this summer, also monitoring the situation, Carvalho admits his future at Sporting is uncertain.

"Will I stay at Sporting? I don't know. I'm going back to Portugal and then we will see," Carvalho told MaisFutebol.

Meanwhile, Sporting have signed Dundee United teenager Ryan Gauld in a deal worth £3m. The highly rated 18-year-old has signed a year deal with the club that also includes a £48m release clause.