The Reds boss was asked for his views on the candidates for the Sir Matt Busby trophy, with voting on the prestigious award starting on Monday for fans across the globe.
"I think we've got two developing players, first of all, in Rafael and David De Gea," explained Sir Alex. "They have had outstanding seasons.
"Then there is Michael Carrick and Robin van Persie. That is the four and I wouldn't like to choose between them. I think they have definitely elevated themselves this season."