Chelsea striker Olivier Giroud admits they need to focus more defensively after their 4-3 Europa League win over Slavia Prague.

The France centre-forward finished off a great move to extend Chelsea's aggregate lead over the Czech side to 4-0, but by the end of the game it was 5-3 in the Blues' favour.

"We started the game very well, we have been efficient," said Giroud.

"Scoring four goals in a half is very nice but obviously after the half-time, in the second half, we should have kept control of the game but they [Slavia Prague] scored two nice goals with long shots from distance.

"We could have put more pressure on the ball but we knew this team was not going to give up so we have been under pressure until the end.

"We dropped a little bit of our intensity and made some technical mistakes. It is a game of two halves and we need to learn to play the intensity of the first half in the second half. We need to learn from the mistakes we made in the second half.

"The most important thing was to win this game and we took a lot of pleasure on the pitch, especially in the first half, but obviously we need to be more solid in the second half."