Manchester United boss Sir Alex Ferguson says Rafael da Silva and David De Gea were key to this season's title triumph.

Ferguson says this season's triumph has been built around a fab four of goalkeeper De Gea, defender Rafael, midfield general Michael Carrick and the Premier League's top scorer, Robin Van Persie, who will be the centre of attention on his return to The Emirates today.

"They are the four I'd say have been our best players this season - I wouldn't like to choose between them," said Ferguson.

"You've got two developing players in Rafa and De Gea, who have been outstanding this season. Then you've got Carrick and Van Persie. They have elevated themselves this season, definitely."