World Cup-winner Mata has established himself as a key figure in the Blues squad, and if he was unsettled by suggestions he would be used as a makeweight in the pursuit of Manchester United striker Wayne Rooney - claims Chelsea swiftly dismissed - he is now intent on proving his worth.
"Everyone wants to feel important for the club," Mata said.
"I feel it, I'm very happy and enjoying training with the new manager, and I hope I can improve on the last two seasons."
Mata and the five other Blues players involved in the Confederations Cup - Fernando Torres, David Luiz, Cesar Azpilicueta, Oscar and John Obi Mikel - missed the tour of Asia and joined up with the Blues squad for the remainder of the pre-season fixtures in the United States.
The last 10 days have been former Valencia midfielder Mata's first taste of working under Mourinho, who called him earlier in the summer to assure him he was part of his plans.
Mata, who has won the Champions League, FA Cup and Europa League in his first two seasons at Stamford Bridge, hopes the current squad can achieve similar successes to those enjoyed in Mourinho's first spell, from June 2004 to September 2007, when they won back-to-back Barclays Premier League titles and numerous domestic cup competitions.
"We're really looking forward to starting the season with him and we are all excited about it," Mata added.
"Jose did a really great job here a few years ago and I think that we can do it again."
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