Chelsea needed a second-half goal from Salomon Kalou to earn a narrow victory at West Ham United in Saturday's London derby.
The winning goal came on 55 minutes when Frank Lampard sent the ball over to Kalou, who did well to score from close range.
The Ivorian went from hero to villain some minutes later though as it was his foul on Herita Ilunga that earned the Hammers a penalty kick, but goalkeeper Petr Cech parried Mark Noble's attempt to save the Blues.
Although Guus Hiddink's men have no reason to complain as things could have ended worse, Chelsea did deserve the win.