Manchester United target Marcos Rojo has submitted a transfer request at Sporting Lisbon after Louis van Gaal bid £15.9m for the World Cup star.
United have moved quickly for the versatile defender after missing out on Thomas Vermaelen to Barcelona.
The 24-year-old played every game for Argentina at the World Cup, including all 120 minutes of the final against Germany, and has been highlighted by van Gaal because of his ability to play centre half, left back and left wing-back.
Sporting are said to be considering United's bid but the player has seemingly signalled his intent to leave the Estadio Jose Alvalade to join the Old Trafford club.
The BBC reports Rojo is so determined to leave the Portuguese club that he is willing to go on strike to force the transfer through.
Van Gaal had been targeting his compatriot, Ajax captain Daley Blind, but the move for Rojo now seems to be entering its final stages ahead of United's Premier League opener against Swansea on Saturday.
Southampton boss Ronald Koeman had hoped the Argentine would join the south coast club as a replacement for Dejan Lovren, but that is now likely to amount to nothing after United ramped up their interest.
Rojo's signing would be United's third of the summer after completing moves for Ander Hererra and Luke Shaw.
The 20-times league champions had been linked with a move for German World Cup winner Mats Hummels, but the centre back has since ruled out a move to the Premier League and is committed to Borussia Dortmund.
Another left-sided player linked with United is Angel Di Maria, the Real Madrid winger, who has been ruled out by French champions Paris Saint-Germain as "too exensive" and is reportedly available for €50m (£39.7m).