Bayern Munich come into the season on the back of a first trophyless campaign in 11 years.
Leverkusen have not lost a match in Germany in May 2023.
Thomas Muller bagged a brace, while Harry Kane and Kingsley Coman also got on the scoresheet.
Bayern Munich have been searching for months but have been knocked back by several candidates after their first trophyless season for 12 years.
Manchester City kick-off their Premier League title defense away at newly-promoted Burnley at Turf Moor on Saturday.
Burnley still have seven games to play, making their promotion the quickest of the Championship era.
Burnley boss Vincent Kompany said even he is surprised at the speed at which his side secured promotion to the Premier League after they won 2-1 at Middlesbrough on Friday
Burnley manager Vincent Kompany endured a nightmare return to Manchester City on Saturday as Erling Haaland scored his sixth hat-trick of the season in a 6-0 rout that sent Pep Guardiola's men into the FA Cup semi-finals
The 36-year-old Belgian retains strong emotional ties with City and, although he would not comment directly on the charges, he said it was wrong for outsiders to point the finger of blame at his old club.
Anderlecht coach Vincent Kompany was left "disgusted" after he said he was the target of racist abuse during Sunday's Belgian league game against Club Brugge.