Frank Lampard believes Chelsea may struggle without the suspended Ashley Cole when they face Barcelona at Camp Nou.
Cole picked up a yellow card in the 4-4 draw with Liverpool on Tuesday night and will now miss the first leg of Chelsea's semi-final tie against UEFA Champions League favourites Barca.
The Spanish side have been in supreme form all season, especially at home, with Lionel Messi the pick of their frightening array of talent.
The Argentine has tormented many opponents by cutting in from the right and Lampard is concerned that Cole will not be there to try and stop him.
"Losing Ashley is a huge blow. He has been absolutely outstanding this season," said the midfielder.
"Lionel Messi is the best player in the world by some distance at the moment and will be on the right wing. If you wanted anyone to play against him it would be Ash.
"Unfortunately he got a yellow card but we have to try and keep together, find someone to come in and do a good job against him for the team."
Lampard is wary of the threat Barcelona will present but is confident Chelsea can progress to the final, just as long as they cut out the defensive errors that allowed Liverpool to score four goals at Stamford Bridge.
He 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.
"If we are going to beat Barcelona we need to play at the level we achieved in the first leg against Liverpool when we won 3-1.
"It will be a very tough game because of the way they're playing, but we know what to expect, particularly in the away leg.
"Barcelona are probably favourites at the moment because of the way they're playing, but being favourites doesn't mean you go through.
"Barcelona are the form team in Europe, if not the world. They've been like that all season so there can't be a tougher match for us in this competition."