The 23-year-old Spaniard has quickly adapted to life in England, making him a difficult player for the manager to leave out, despite the impressive form of others in his position.
Speaking about Mata, Villas-Boas told chelseafc.com: "Players we have been using on the left have been performing to a very high standard, Malouda, Kalou and even Anelka on the left, so I think what he has been able to do is adapt pretty quickly to the Premiership. He has taken the minimum time which helps us benefit from his abilities.
"He is a player who likes to find different spaces to receive the ball, and creates spaces. His movement allows the other players to find him in different positions. His individual characteristics have brought these movements to our game but the other ones have been playing fantastically well.
"Flo likes to come inside but not so much as Juan, and has been doing it well. Malouda is for the last two years the player with most assists for goals, and he did that against Genk one more time so I am really happy with Malouda [also]."