Mata, who scored two of Chelsea's goals in the win, admitted that the 4-0 scoreline was harsh on the Danish side.
"It was nice to score and to get this result. We are now on top of the group which is what we are aiming for," Mata told Chelsea's official website.
"It makes up for the Juventus game. This game was very difficult for us, but we go back to London with a very important three points.
"After seeing the ball possession, to win 4-0 is harsh. They played well on the ball and had some quality players. It wasn't as easy as 4-0 sounds and they had a good opportunity to score at 1-0."
Chelsea currently top Group E on goal difference.