Chelsea captain Cesar Azpilicueta says they almost paid for their errors after defeating Europa League opponents Slavia Prague 4-3 on Thursday.

A double from Pedro, Olivier Giroud's 10th Europa League strike and an own goal by Simon Deli had Maurizio Sarri's side in control with a 4-1 lead at the break.

But another woeful performance after the interval nearly cost them dearly as Slavia Prague struck two goals through Petr Sevcik to ensure a nervy ending at Stamford Bridge.

"I think it's our mistake and one we are making very often," Azpilicueta told BT Sport.

"The result is not easy and we keep conceding early goals and making the same mistakes in the second half.

"We put ourselves in a position where we could control the game but we suffered until the end.

"It's not the way we want to win the trophy but we're in the semi-finals. They [Slavia Prague] are a tough side, they never give up and showed that when they beat Sevilla in the last round."