Rumours over the Spaniard's future at Stamford Bridge have been rumbling due to the 25-year-old's failure to secure a regular place in the team.
"I have been working hard and want to show everyone that I can play and that everything is okay," the Daily Star quotes Mata as saying.
"In my career I have played in three different positions. In the beginning I was a left-winger, then I played on the right and last season as a number 10.
"I feel comfortable playing in any offensive position – it is better if a player can play in lots of different positions rather than just one."
Spanish champions Barcelona are said to be monitoring Mata's situation ahead of the January transfer window.