Angel Di Maria believes Marcos Rojo has the aerial power to end Manchester United's struggle against set pieces.
Manager Louis van Gaal has said it is "very difficult to defend" against Stoke and Cambridge, two of United's recent opponents, who have had bigger teams than the former Premier League champions.
But though the 6-foot-1 Rojo is among the smaller centre-backs, his Argentina teammate Di Maria thinks the former Sporting Lisbon player's fighting spirit and natural spring can help him win headers in his own box.
"Off the field he's really relaxed, a real family guy, a really good person," he told reporters.
"But on the field he's a very aggressive player, very strong. He plays to the death. He puts it all on the line when he's on the field and I know he will be a great asset to United.
"He does great with free kicks in the area -- he's great at headers. He targets the ball and jumps high. I think he is a great player when it comes to headers."
Rojo, who joined United for 16 million pounds in August, was a teammate of Di Maria's as they helped their country reach July's World Cup final.
And the winger believes he earned his move to Old Trafford, adding: "The first time I met him was with the national team. He's a great guy -- very modest, very laid back, very professional and after so many great games and a great World Cup he deserves to play for a great club like United."