Brendan Rodgers wants Celtic to leave their respect for Barcelona in the dressing before the Champions League clash at Parkhead on Wednesday night.
The Hoops boss saw his side thrashed 7-0 when the two sides met in their Group C opener in September.
In a remarkable night in the Nou Camp Lionel Messi helped himself to a hat-trick and Luis Suarez a double, with Neymar and Andres Iniesta also notching in the demolition of the shellshocked visitors, who saw striker Moussa Dembele have a penalty saved at 1-0 for the home side.
Celtic are bottom of the group with two points from four games and need one win out of their last two fixtures - they play Manchester City away next month having drawn 3-3 with the English club at Parkhead - to have a chance of playing European football after Christmas.
Rodgers, for one thing, is looking for the Scottish champions to be more aggressive against table-topping Barca.
He said: "You have to respect that they're good players, but you cannot take that into the game, you have to go in with a clear mind and impose your style on the game.
"That's the message from ourselves.
"It was a difficult night for us, but it was also about learning and clearly we've shown from that performance that we have learned from it.
"This is the next opportunity to show, against them as direct opponents, and of course we have the incredible support here behind us.
"It should be an unbelievable atmosphere, but they are a team that has played in atmospheres throughout the world, so they're used to dealing with that pressure.
"We have to play how we're best playing, which is really aggressive and on the front foot, having the tactical plan in order to be really aggressive in the game.
"We have to fight and ensure that we do everything we can to try to stop them - but it's not easy."
Rodgers revealed that Leigh Griffiths will be given every chance to prove his fitness ahead of kick-off.
The Hoops striker is suffering from a tight hamstring which kept him out of the 1-0 win over Kilmarnock on Friday night.
Rodgers said: "He did the warm-up with the group on Tuesday morning and he's making good progress."