West Ham United picked up their first win of the Premier League season despite being reduced to ten men against Chelsea.
Goals from Nayef Aguerd, Michail Antonio and Lucas Paqueta saw the Irons come away with all three points despite being a man down for the majority of the second half.
Mauricio Pochettino's Chelsea know that they will have to improve and do so rapidly if they are to compete at the top end of the league this season.
It was a disappointing defeat for the Blues, who had high hopes going into the match after showing their fighting spirit against Liverpool last week.