Mata impressed in their Champions League rout of Steaua Bucharest.
"I'm happy to play, I'm happy with how I played in the last three games and I'm happy with how the team played," Mata told chelseafc.com.
"I just try to do my best in every game and do everything I can in order to help the team. That's what I've been doing and I'm feeling good.
"I'm really pleased to be back in the Spain squad and, obviously with the national team, my target is to play in the World Cup."
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