In fact, Brown reckons the away game in Lisbon against Benfica in a fortnight and the final Group G tie at home to Spartak Moscow next month will carry more significance in terms of qualifying for the last 16.
He said: "It's a tough group and we have three games to go.
"Barcelona at Celtic Park is going to be hard and great occasion for us.
"But whatever happens in this match, we still have another two big games to go.
"Spartak here and Benfica away are going to be just as big as Barcelona at home.
"We have already won our first game away in the Champions League ever, so that shows we are going in the right direction."
Of course, anything injury-ravaged Celtic could take from the match against Lionel Messi and Co. this evening to add to the four points they already have would boost their qualifying chances.
After taking Barca so close in the Nou Camp two weeks ago, the Hoops are right up for this game, even though Emilio Izaguirre, James Forrest, Lassad Nouioui, Anthony Stokes and Thomas Rogne are out and Georgios Samaras faces a last-minute fitness test.
Gary Hooper is also expected to miss out, which is a double blow for the striker who was set to be called up to the England squad for next week's friendly match against Sweden.
Even with such a depleted side, Brown – who will again ignore his hip injury to lead the team – is confident the Hoops can compete effectively against Barca.
"Barcelona are probably one of the best teams ever, the way they keep the ball and with their movement," he said.
"But we're going to try and get something out of this game.
"First and foremost we have got to defend really well and try to counter attack.
"We have a few injuries, but we have young lads coming in and doing really well.
"We will have to try and create a few more chances than we did in the Nou Camp, and be a bit calmer on the ball and get a few more passes in.
"But it's hard when you are playing against a team who press you so high up the park.
"We can learn from that. If we want to be in this competition year in year out, we have to try and press teams high up the park."
Brown is confident they have already learned from the last-minute defeat in the Nou Camp.
He said: "We have to stay focused for 90 minutes and injury time as well.
"A draw would be a fantastic result."