The Blues beat London Arsenal rivals 2-0, thanks to a goal each from the Spanish pair. The right back scored his first goal for the club since moving to London from Marseille 14 months ago.
While the 25-year-old has been the subject of questions surrounding Jose Mourinho’s team selection, Mata was more focused on Azpilicueta’s strong performance, and not his own.
“We tried our best as it was a difficult game because Arsenal are playing really well in the Premier League and Champions League,” Mata told Sky Sports.
“But today I’m more happy for Cesar, to be honest. He trains more than anyone and he fully deserves the goal and the celebration more than anything.
“The manager is the one who makes the decisions, but I always try my best for this club and that’s what I’ll always do. Today I enjoyed it, and I felt proud for the fans, but I’m really happy for Cesar.”
Azpilicueta opened the scoring for the Blues after a mistake from Arsenal youngster Carl Jenkinson. And Mata’s 65th minute strike wrapped up the match, and booked Chelsea’s place in Round 5 of the competition.
The result at the Emirates means that Arsene Wenger is still looking for his first victory over Mourinho.