Mata thrilled with Chelsea's Azpilicueta signing
The Blues completed the £7million transfer of the 22-year old Spanish right-back from Marseille which thrilled his fellow countryman who knows him well from his playing days in Spain.
"I used to play with him before the Olympics as well as at the Under 21s and earlier," Mata told the club's official website.
"He is a strong running right-back who has pace as well, so I think he is already a complete player.
"He is such a nice guy, a young player who is very clever on and off the pitch, so he will be very good here."