Frank Lampard has warned Chelsea they can forget about beating Champions League favourites Barcelona if they repeat their dire defensive performance in the thrilling 4-4 draw with Liverpool.

The Blues' incredible 7-5 aggregate win over their Premier League rivals set up a last-four tie with the Spanish league leaders but they will have to rectify the problems that have seen them concede seven goals in the last two games.

Petr Cech insisted today that he remains fully confident in his own ability but he again looked nervous in goal and was badly at fault for Fabio Aurelio's opener for Liverpool.

To make matters worse, Chelsea will have to make do without a recognised left-back to mark Lionel Messi for the first leg at the Nou Camp on 28 April as Ashley Cole will be suspended.

Lampard said: “We have to look back at the mistakes we make as a group in conceding goals. We have to be strong and we need to tighten up defensively.

“Barcelona are the form team in Europe, if not the world. They have been that way all season. If we are going to beat them, we need to play at the level we achieved in the first leg against Liverpool when we won 3-1. We need that and more against Barcelona to win.

“Not having Ashley for the first leg is a huge blow, as he has been outstanding this season. Messi is the best player in the world by some distance at the moment, and if you wanted anyone to play against him, it would be Ash.”

Cech said he is not expecting to be dropped for Saturday's FA Cup semi-final and claimed he would bounce back against Arsenal at Wembley.

He said: “I would be disappointed to be left out against Arsenal. Who wouldn't be? This is a question for the manager, but one bad goal can't change what you have been doing all season. You have to show your confidence in training and in games.

“If you go to speak to the manager, you can say whatever you want, but he needs to see your answers on the pitch, not in his office. In any case, I am sure we won't defend as badly again on Saturday.

“It is the first time in my Chelsea career that I have conceded so many goals in two consecutive games, and the first time I have made mistakes in both of them.”

Lampard's two late goals proved crucial for Chelsea after Liverpool had raced into a 2-0 half-time lead through Aurelio's free-kick and Xabi Alonso's penalty.

Strikes from Didier Drogba, Alex and Lampard looked to have sent the Blues through, before both Lucas and Dirk Kuyt scored.

Lampard's second in the 89th minute finally killed off the tie and Liverpool must now concentrate on overhauling Manchester United to clinch their first domestic title since 1990.

There will be a memorial service held at Anfield today to mark the 20th anniversary of the Hillsborough disaster, in which 96 Liverpool fans died, and Reds goalkeeper Pepe Reina said: “We tried our best for the 96. We were playing as 11 guys, but we were also lifted by 96 souls.”