The Brazilian made the switch to the Volkswagen Arena in August on a five-year deal, after failing to establish himself as a first-team regular at Bayern.
Wolfsburg have made an inconsistent start to the new Bundesliga campaign, with three wins and three defeats from their six matches so far.
But Gustavo believes that there is no greater incentive for victory than playing a team he deems to be the best in world football.
In an interview with Bayern's official website, he said: "It is certainly a bit different from a normal away day.
"I played at Bayern for two years and now I'm coming back as an opponent. We are playing against a very good team, that's exactly what every player wants.
"Bayern is the best club in the world after the treble last year, you can definitely say that.
"Each opponent will try to beat them.
"It won't be funny (playing against his former team-mates), we had training and often played against each other."
