Celtic manager Brendan Rodgers urged his side to learn from their mistakes in the Champions League as they aim to shock Atletico Madrid in Glasgow on Wednesday.
The Scottish champions have lost both their opening two games in Group E to Feyenoord and Lazio.
But defeat at home to the Italians three weeks ago was particularly painful as Celtic led early on and dominated most of the match before Pedro scored a 95th-minute winner for Lazio.
“The Lazio game was a real indication of the level. We played very well but one moment at the end of the game costs you the points,” said Rodgers.
“That’s a reminder of the level but it doesn’t stop you being persistent and looking to fight. The fans expect us to fight and run in order to play quality football. That’s the style of this team and we will continue to do that.
“It’s life, isn’t it? Adversity is some of the best learning that you have. The pain was numbing at the end because we didn’t feel we deserved that, but I don’t want to be taking condolences after losing games of football.
“I respect the level we are at and it’s up to us to see if we can be more progressive in our results.”
Celtic have not won a Champions League group game since Rodgers’ first spell in charge of the club in 2017 and the drought is even longer at home.
Once considered a fortress in European football, the Hoops’ last Champions League win at Celtic Park was a decade ago over Ajax.
Rodgers has targeted at least a third-place finish to secure Europa League football in the new year, but realises it could be win or bust for his side against the Spanish giants.
“It’s important for us, if we are going to progress at any point in any of the competitions, we have to take something from the game, otherwise it’s a hugely difficult challenge for us,” added Rodgers.
“But we are excited about the challenge and I am really looking forward to seeing how we take that challenge on.”
