The Blues are reportedly leading the chase to sign the 23-year-old for a fee of €27m (£23.6m), and the former Porto manager has yet to deny the club's interest in the player.
"He's a good player, a very good player," the Blues boss told reporters. "He's not our player but he's an interesting player.
"His curriculum speaks for itself. He's a player who scores and assists and he can add to any squad in the world."
Mata, who starred in Spain's Under-21 European Championship triumph earlier this summer, was also part of Vicente del Bosque's 2010 World Cup winning side.