Chelsea boss Thomas Tuchel has opened up on his side's missed chances as the Blues fell to defeat in east London on Saturday.
Goals from Thiago Silva and Mason Mount were not enough as West Ham scored three, including two second-half strikes to win the match.
Speaking to BT Sport after the match, Tuchel discussed his side's missed chances.
He said: "We wanted to (finish the game off). We could not finish with clear chances and be more ruthless. We struggled a bit, also in defending."
Chelsea ended the match with Romelu Lukaku, Mason Mount, Callum Hudson-Odoi and Christian Pulisic all on the pitch but could not find a goal in the second-half before Arthur Masuaku scored the winner for the Hammers.
The loss opens up the opportunity for Liverpool and Manchester City to leapfrog Chelsea in the Premier League table as the Blues could see themselves down as far as third in the league going into next weekend's matches.
Tuchel's side will be hoping to come back and show an improved performance when they face Zenit on Wednesday before the Blues host Leeds in the Premier League next Saturday, needing a win to continue their title challenge.
Lukaku could start in these matches, despite Chelsea looking less fluid with the forward on the pitch due to Kai Havertz's injury.
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