Manchester United could challenge Arsenal for the signature of William Carvalho as Louis van Gaal scrambles to bring in a defensive midfielder before the transfer window closes on Monday.

United are thought to have revived their interest in Carvalho after Sporting Lisbon lowered their valuation of the Portugal midfielder, whom they were initially refusing to sell for less than the buyout clause of €45 million (about £36 million) stipulated in the 22-year-old’s contract.

Carvalho is now likely to be available for closer to €30 million and United are believed to be weighing up the merits of a move in the wake of their protracted pursuit of Marcos Rojo from the Portuguese club.

The Argentina centre half joined United for £16 million eight days ago, although