The German club twice came from behind to defeat Fortuna Dusseldorf 3-2 in the Bundesliga on Saturday, with Boateng scoring the winner.
"As a team, we showed great spirit," he told Bundesliga.com. "The way we came back is important in the context of Wednesday's game against Arsenal. We're feeling positive and full of confidence."
Bayern won the first leg 3-1 at the Emirates Stadium in London last month.