The midfielder came on as a late substitute in the Euros final as Spain recorded a third straight tournament win in Poland and Ukraine, scoring the last goal in their 4-0 final destruction of Italy, but at the Olympics it was a different story, as they failed to score a single goal and surprisingly crashed out of the competition at the group stage.
"I feel really good and confident for the new season," Mata told Chelsea TV. "Myself and Oriol have been looking forward to coming back and I'm happy to be here.
"The Euros were the best moment of the summer for me. Another European Championship for Spain, I had the opportunity to play in the final, I scored the last goal and it was amazing.
"The Olympics was a good experience as a sportsman, but we were so unlucky. We deserved more but we didn't score so it was impossible to go through.
"I think it will be a good season for us. Personally, I will try to play more games than last season. For sure, our desire is to win another trophy, either the Premier League or Champions League. These competitions are very important for us and we will try to do our best."