Sir Alex, Michael Carrick and Jonny Evans all praised right-back Rafael following United's 1-0 win against West Ham on Wednesday night.
The Brazilian, who's on our shortlist for the Man of the Match award, produced a defensive masterclass against the Hammers, winning almost every tackle and ball he contested.
The Reds boss repeated his recent claim that Rafael is "maturing and learning from [past mistakes]", while Carrick believes he'll get even better.
"He has progressed every year he has been here," Carrick told MUTV. "He came across at a very young age and it was a big change from Brazil and what he was used to.
"Every season he has got better and better. He has played nearly every game this season and has been terrific. There is still more to come from him, he is still learning the game and is still improving, so it is great for him and he is having a good time."
Jonny Evans was similarly effusive in his praise and insists Rafael sets an example for others when he's on the pitch. "He's been outstanding all season," he said. "There’s not really been anybody challenging for his right-back position but he’s done fantastic.
"With his energy, he really sets the tone for the rest of the players. He’s a credit to himself. People might have thought it would be tough for him with his brother going away but he’s got his head down, he’s working hard and he’s going to be one of the best right-backs in the world, no doubt about that."