Gilberto believes Arsenal will have to produce an outstanding defensive display if they are to secure UEFA Champions League glory.
The Gunners lock horns with Barcelona in Paris on Wednesday and all the pre-game hype has surrounded the battle between Thierry Henry and Ronaldinho.
The pair are regarded as the two premier attacking talents on the planet and how they perform could have a bearing on the outcome.
Gilberto is aware of the talents of team-mate Henry and Barca star Ronaldinho, but feels the outcome will be decided by how well Arsene Wenger's back-line perform.
"If we are not very tough defensively, Barcelona will kill us," Gilberto told The Guardian. "But we must not be afraid.
"If we defend well then we have a big chance to play with belief and happiness - and win the Champions League."
Gilberto will be charged with the task of protecting the back four and he has urged his team-mates to adopt a positive attitude at Stade de France.
"Barcelona are definitely one of the world's best teams - but they're not unbeatable," he added. "We need to be positive in attack and not make any mistakes in defence because they have the players, especially Ronaldinho, to hurt you.
"We are good team-mates for Brazil - but this will be the first time I've played against Ronaldinho.
"He's the number one player in the world and, without him, Barcelona are not so dangerous."
Wednesday's showpiece event could be Henry's last in Arsenal colours, as he has yet to pledge his future to The Gunners, and Gilberto is in the dark as to his team-mate's next move.
"When we hear that Barcelona want Thierry next season, we hope very much he will stay with us," added the Brazilian midfielder. "We know how important he is for our team.
"He's a fantastic player and a very nice guy. But even at Arsenal, no one knows what he will do after this game."