Manchester United boss Louis van Gaal is confident Marcos Rojo will prove a shrewd signing. The 24-year-old arrives at the club on the back of a successful World Cup campaign with Argentina, who beat Van Gaal's Holland side in the semi-finals.
The defender also brings with him a poor disciplinary record of 21 yellow and four red cards in his 49 league appearances for Sporting CP.
Van Gaal is a big fan of Rojo, but he says the player must learn to be calmer on the pitch.
"He has to be aggressive in the right moment," the Manchester United manager said.
"When I have to say something about him that I have to criticise, that is it - he has to control himself in every moment.
"He can improve in that and maybe I can help him."
The defender's performance against Holland in the final-four clash in Sao Paulo alerted Van Gaal to his capabilities.
"I had to analyse Argentina when I was playing against him and in that video I was already enthusiastic about him," said Van Gaal, who has an open idea about where the player can slot into his XI.
"I think Marcos fits into the profile as a left central defender or a left wing-back," he said.
"He played for Argentina as a left wing-back but at Sporting Lisbon he played as a central defender.
"He had a fantastic World Cup. I am very pleased."
