The Scottish champions will host the Blaugrana at Celtic Park in Group G.
"If we get something out of the game, it'll give us a strong foothold in the group," said Lennon. "We want to get a positive result. We know it's going to be hugely difficult; I can't see any weaknesses in Barcelona.
"They are strong in every part of the park. We hope we can catch Barcelona on an off night.
"We need to keep the ball better but it's easier said than done. They don't change – they force other teams to change."
Celtic are currently second in the group with four points from three matches, five points behind leaders Barcelona.