Diego Costa is delighted with the progress he's enjoyed at Chelsea.
Costa moved to Chelsea from Atletico in a £32million transfer deal this summer and he has not disappointed.
He scored his ninth league goal in Sunday's 2-0 triumph over Arsenal that lifted Chelsea five points clear at the top of the Premier League standings.
"Things are going very well, but not just for me but for Chelsea," Costa said. "I'm delighted.
"Against Arsenal it was complicated but we managed to win."
