Chelsea midfielder Nemanja Matic has talked up the impact that Diego Costa has made since his arrival at the club.
The Spain international, who was signed for £32m from Atletico Madrid in the summer, has scored seven goals in four games and was awarded the Player of the Month gong for August.
Matic told Chelsea's official website: "Diego is very important for us, he's a great striker, he scored three goals [against Swansea City] and that's why Chelsea bought him.
"I hope he will continue to score goals; he works very hard on the pitch, not only offensively but defensively as well."
Costa is currently top of the Premier League scoring charts.
