Carlo Ancelotti has called on Chelsea to be more focused at set-pieces following the 2-1 defeat at Aston Villa.
Chelsea headed into Saturday's game in the Midlands top of the Premier League table and took a 15th minute lead through Didier Drogba's long-range effort.
However, Richard Dunne equalised just past the half-hour mark for Villa before James Collins headed the winning goal for the hosts early in the second half.
Both goals came from Ashley Young corners, with Villa's centre-halves allowed to meet the winger's deliveries unmarked following poor marking by Ricardo Carvalho and Nicolas Anelka respectively.
Ancelotti was unhappy with the lack of concentration at set-pieces and the Chelsea boss admits it is an area his team must improve upon quickly.
"We lost the game because we had two set-plays," Ancelotti told Sky Sports. "We need to be more focused on the situation.
"Chelsea played a good game and we don't want to lose the game in that situation, only if the other team play better than us. Aston Villa were very able on the set-plays.
"We want to do better for sure. We need more concentration."
Ancelotti is happy with the form of Frank Lampard even though the England man has now failed to score in his last 10 club games.
The Chelsea manager said: "I don't know why he is not scoring, but I think he is doing a very good job. Against Villa he played very well.
"We had a lot of space to pass the ball through to the strikers and had a lot of chances in the second half.
"I am happy with Lampard's play. I am not interested in the fact that he has not scored. He is working for the team and working very well."