Mata feels he's beginning to find his best form for club and country after helping Spain book their place in Brazil next summer.
"I am very happy to win, to qualify first mathematically and to go out and score," said the former Valencia man.
"In the last qualifiers it has been very difficult to score because it has been tight."
Mata has been on the fringes of Mourinho's thinking so far this year but the Blues' No.10 has overcome his injury niggles and is raring to play his part.
"I've been playing several games and I think I am at a good level," he added.
"I feel fine. When I had a difficult time that was in pre-season due to injury."
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