Pep Guardiola has warned Manchester City they will need to keep their discipline to have a chance of beating Barcelona tonight.
City have lost all five of their games against the Catalan giants in the past two-and-a-half years and had a man sent off in four of them.
The most recent was goalkeeper Claudio Bravo in City's 4-0 loss in their first Champions League Group C meeting at the Nou Camp a fortnight ago.
Former Barcelona boss Guardiola, well aware of how ruthless his old club can be, knows they must avoid a repeat as the sides meet again at the Etihad Stadium.
Guardiola said: "Yes, you have to learn. It's always difficult to win Champions League games and it's always difficult against Barcelona 11 v 11, but when it's 10 v 11 it's almost impossible.
"Sometimes (they were) unfair and last time it was from a mistake, but at that level it's impossible to achieve your targets (without discipline)."
Guardiola could have been aiming his words at the player who joined him for pre-match media duties, Nolito.
The Spain forward was sent off against Bournemouth in September for aiming a headbutt at an opponent and was booked following a similar incident at West Brom on Saturday.
Asked about the matter, Nolito said: "I had no intention to hurt any other player but I have to show an example for children and other players. Hopefully it will not happen again."
Bravo's red card - following Martin Demichelis, Pablo Zabaleta and Gael Clichy in being sent off against Barca - means he is suspended for the return clash and Willy Caballero will take his place.
Caballero was preferred to Joe Hart in the early weeks of the season as City conducted the search for a better ball-playing keeper that led them to Bravo and Guardiola is confident he can deliver.
He said: "He's helped me very much from the very first few games and I like him on a personal level.
"Every time he's played he's played well, he gives me a lot of confidence. If he plays well we're happy. If he doesn't we will try and help him but we have no doubts about him."
After drawing with Celtic, the loss to Barcelona has left City in a fight for second place in the group with the Scottish champions and Borussia Monchengladbach.
Guardiola is aware of the importance of the fixture, but knows just how well City will need to play to get anything from it.
He said: "We have to play like a final. It's not a final for them, it is a final for us.
"There are just three games left and we dropped two points in Glasgow, so we have to recover those points in the next two games. I have never entered a match thinking we can't win but we have to play almost perfectly."
Top scorer Sergio Aguero seems likely to start after being surprisingly left out at the Nou Camp in a tactical move to bolster the midfield that backfired.
Guardiola said: "I think we know what we have to do to beat them.
"They know us but hopefully our quality up front will make a difference."
The Premier League leaders also go into the game with confidence restored having ended a six-match winless sequence with an emphatic 4-0 defeat of West Brom at the weekend.
"Winning the last game will help us a lot," said Guardiola.
"When you play a game having won the previous one the feeling is much better. We play the best tomorrow and we're going to try to win."