Antonio Conte has praised a Diego Costa for his focused performances for Chelsea this season, but insists the in-form forward can still get even better.
Costa is the Premier League's top scorer with 12 goals, one more than Arsenal's Alexis Sanchez, and struck the winner in the 1-0 home triumph over West Brom on Sunday.
The Spain international is a key member of a Chelsea side that leads the league tables after a stunning run of nine successive wins.
Despite Costa's outstanding personal displays, Conte feels there is even more to come from the 28-year-old.
"Diego is playing the season in a fantastic way and I'm pleased for him and the fans," Conte told the media.
"He's showing great patience in the right way. He's very focused on football, making the right movements and attacking the space. But I think he can improve."
Conte takes his squad to Sunderland on Wednesday looking to make it 10 in a row in the league.
However, the Italian also has to take into consideration the effects a packed December schedule can have on his players, with the victory over West Brom the first of six games in the space of 24 days.
"We are ready to face a lot of games in a few days. We are working very hard to face this Christmas period. Now it's important to start in the right way," he told the club's official website.
"It's a new experience for me and my family. Usually over the Christmas period I'm used to having a break with my family, but now it's fantastic to have this experience, to play during the Christmas period in a new country.
"In the past I always watched the English games in this period on TV, and now to live this atmosphere is fantastic."