Schalke recovered from two goals down to claim a 4-2 victory over Mainz on Sunday as the hosts suffered their first defeat of the Bundesliga season.
It all looked so easy for Mainz in the first half at the Mainz Arena, with goals from Andreas Ivanschitz and Elkin Soto putting them within reach of a third straight win from three games
However, Schalke were transformed in the second half with goals from Klaas-Jan Huntelaar, Benedikt Howedes, Joel Matip and Christian Fuchs earning Ralf Rangnick's side a win that nobody would have imagined possible at half-time.
Following Mainz's slip-up, Hannover went joint top of the fledgling table alongside Borussia Monchengladbach on seven points although they were denied victory as Hertha Berlin struck late for a 1-1 draw.
Pierre-Michel Lasogga's tap-in seven minutes from time rescued a point for newly-promoted Hertha after Sergio Pinto's free-kick had given Hannover the lead in the first half.
Bundesliga champions Borussia Dortmund bounced back from last weekend's defeat at Hoffenheim with an efficient 2-0 home victory over Nurnberg on Saturday.
Robert Lewandowski put Jurgen Klopp's side ahead four minutes into the second half and Kevin Grosskreutz made the points safe with a second goal - courtesy of a wicked deflection off Phillipp Wollscheid - 10 minutes from time.
The result moved Dortmund to within a point of leaders Borussia Monchengladbach in the fledgling league standings, while Nurnberg remains in the bottom half.
Hoffenheim made it back-to-back wins to leave Augsburg still searching for a first victory since their promotion as they ran out 2-0 victors.
Ryan Babel gave the visitors an early lead with Sejad Salihovic scoring from the spot in the second half as Holger Stanislawski's men built on last weekend's success over champions Borussia Dortmund.
Bayern Munich swept aside woeful Hamburg 5-0 at the Allianz Arena.
Daniel van Buyten gave the home side an early lead before Franck Ribery swiftly added a second.
Arjen Robben put the result beyond doubt before the interval and Mario Gomez and Ivica Olic were on target in the second half.
Werder Bremen scored twice in the final four minutes to claim a thrilling 5-3 home win over Freiburg.
The visitors twice came from behind to draw level at 3-3, but Aaron Hunt's 87th-minute penalty and a last-gasp Beltrame Wesley strike won it for Bremen.
Papiss Cisse netted twice for Freiburg, opening the scoring in the seventh minute and making it 2-2 shortly after the break after Clemens Fritz and Claudio Pizarro had turned the game in the hosts' favour.
Marko Arnautovic put Bremen back in front in the 65th minute, but Stefan Reisinger looked like he had rescued a point when he made it 3-3 six minutes from time.
Stefan Kiessling took advantage of an error by Stuttgart goalkeeper Sven Ulreich to steer Bayer Leverkusen to back-to-back Bundesliga wins with a 1-0 victory.
Ivo Ilicevic opened the scoring for Kaiserslautern after 17 minutes away to Cologne but Mato Jajalo netted two minutes later to ensure the spoils were shared.
Borussia Monchengladbach claimed an impressive come-from-behind 4-1 victory over Wolfsburg on Friday.
The visitors took a 12th-minute lead at Borussia-Park when Makoto Hasebe rounded off a fine team move by lashing into the bottom-right corner from the edge of the area.
But Monchengladbach were level less than three minutes later when Raul Bobadilla capitalized on a defensive error from Simon Kjaer to set up Marco Reus, and went ahead through a Filip Daems penalty just after the half-hour before Bobadilla nodded home a third on the stroke of half-time.
Reus then sealed an emphatic victory by netting a fourth goal midway through the second half.