Leverkusen raced into a 3-0 lead, scoring all three goals in 16 frantic second-half minutes before Bayern netted twice in two minutes to set up an electrifying finale.
Tranquillo Barnetta's thundering drive from 20 metres gave the hosts the lead before Arturo Vidal and Patrick Helmes increased the scoreline to 3-0.
Bayern fought back with one from Lucio and Miroslav Klose's close-range header two minutes later but as they poured forward they conceded a fourth goal through Stefan Kiessling deep in stoppage time.
Brazilian playmaker Diego scored twice to steer
Bremen stormed into a two-goal lead, netting twice in the first seven minutes.
Claudio Pizarro did well to control a deep cross inside the box before cutting the ball into the middle for Diego who turned smoothly to avoid two defenders and fire in.
Mesut Ozil got the second when he fired past keeper Andre Lenz from a tight angle on the left.
Wolfsburg pulled one back with Edin Dzeko blasting a Marcel Schaefer cross into the net before keeper Nico Pellatz, making his first senior appearance, could get his hands on the ball.
The 22-year-old Pellatz was to blame for Dzeko's equalising second three minutes before the break when he ventured out to clear a cross and hesitated briefly only to see the Bosnian float his header over him and into the net.
Diego converted a penalty before Pizarro restored the two-goal cushion and then netted his second goal from close range in the final minute.
Hamburg took the lead after 17 minutes when Collin Benjamin's low cross was met by Petric at the near post.
The Croatian added his second when he was left unmarked in the box to control a Marcell Jansen cross and fire home from eight metres. Wiesbaden scored five minutes from time through Sandro Schwarz.