Everton boss David Moyes feels Juan Mata has lifted the play of Chelsea.
Moyes' men face a daunting trip to Chelsea today, where they have not lost in five league games.
But he admitted: "They have added a couple of new dimensions to the way they play and, for me, Juan Mata is the biggest difference I see in Chelsea.
"Mata is probably as close to David Silva as I have seen.
"He has given them a flexibility that they had in their heyday."