Lisandro Martinez has been praised by Manchester United team-mate Luke Shaw.
The left-back admitted that the Argentine has "everything" to be a top player.
He said: "I could see his qualities, feel the passion that he brings, how aggressive he is and he's got an amazing left foot.
"With the ball he's so composed, so good and I think a lot of football nowadays is how well the centre-back can play out. But I think, for me, he's got everything.
"There was obviously a lot of question over his height at the start, which, for me, was nonsense, really. He reads the game so well. With someone that intelligent, I don't think it matters how tall you are or not, wherever you play, as long as you read the game well.
"For me, he does that and I love playing next to him. He's an amazing player and still really young. He's only going to get better and better, I think."