Lampard on the attack over Chelsea's sloppy defending

Barça will seize on errors, says midfielder as tie with Europe's form side looms

As Chelsea recovered yesterday from their night of tension and drama that ultimately turn to joy at Stamford Bridge on Tuesday, Frank Lampard sifted through the evidence and was honest enough to admit that all was not well with the club.

Guus Hiddink's side drew 4-4 with Liverpool in the second leg of their Champions League quarter-final and won 7-5 on aggregate but not without putting themselves through an evening of contrasting emotions while conceding four goals.

That lax defence is proving to be a worry for Lampard, the Chelsea midfielder who scored two of his team's goals. "We have to look back at the mistakes we make as a group in conceding goals," he said. "We have to be strong and we need to tighten up defensively."

In the semi-finals, Chelsea will face Barcelona. The Spanish league leaders hammered Bayern Munich 4-0 in the first match of its two-leg quarter-final series and then played out a 1-1 draw in the second to advance. With Lionel Messi playing well both in the Champions League and in La Liga, and Thierry Henry getting back to his best, Barcelona are favourites to win their third European Cup.

"Barcelona are the form team in Europe, if not the world. They have been that way all season," Lampard said. "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."

Lampard's team-mate, the central defender Ricardo Carvalho agreed with Lampard's assessment. "We have conceded too many goals," he said. "You can watch to learn and improve from mistakes but it will not be a pleasure to watch."

The defenders were not the only ones struggling, however, and goalkeeper Petr Cech took some of the blame after misjudging a 19th-minute free-kick from Fabio Aurelio that went into his net. "I hold my hand up for the first goal. I was caught too easily," said Cech, who has now conceded seven goals in two games and next faces Arsenal in the FA Cup semi-finals on Saturday. "I slipped a little bit but that's not an excuse – it's a goal I shouldn't have conceded."

Cech had other moments of hesitancy, too. "I have never been involved in such a game and I hope I am not going to be again," Cech said. "It's 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."