Cameroon striker Mohamadou Idrissou was both goal-scorer and provider for Moenchengladbach as they upset Leverkusen 6-3 on Sunday in a nine-goal thriller on a weekend of shock results in the Bundesliga.
Leverkusen's Germany goalkeeper Rene Adler had a day to forget as his defence capitulated leaving coach Jupp Heynckes red-faced.
"'Gladbach played very well," admitted Heynckes. "We made a mess of our defensive organisation. We invited 'Gladbach to the party and they punished us."
After Bayern Munich were beaten at Kaiserslautern on Friday, Wolfsburg allowed a 3-0 lead to slip to a 4-3 defeat by Mainz on Saturday as Schalke went down at home to Hanover on a bad weekend for the German league's top teams.
Leverkusen fielded Germany star midfielder Michael Ballack - who was booed off when he was replaced in the second-half - as well as Adler and striker Stefan Kiessling.
But they were out-played by 'Gladbach as midfielder Patrick Herrmann netted twice for the guests which were both set up by Idrissou, who scored himself in the second-half.
"This is an extraordinary day for us," said coach Michael Frontzeck. "We took everything possible from this game and everything worked out for us. But our objective will not change, we want to build on last season."
Stuttgart's poor season start season continued as they were well beaten 3-1 at home by Dortmund. The guests raced into a 3-0 lead after just 37 minutes as Christian Gross-coached Stuttgart were torn to pieces.
It started when defender Marcel Schmelzer fired in a cross which deflected off Dutch defender Khalid Boulahrouz and into the net after five minutes.
Striker Lucas Barrios and midfielder Mario Goetze then both netted before Germany striker Cacau pulled a consolation goal back for Stuttgart, who are bottom of the table after two games.
Hoffenheim are joint early leaders with Kaiserslautern after Ghana defender Isaac Vorsah headed a late goal on Saturday night that gave them a 1-0 win at newcomers St Pauli.
Earlier, Wolfsburg playmaker Diego marked his return to the Bundesliga with a goal, but was unable to prevent his new side's shock 4-3 defeat by Mainz as the home side threw away a 3-0 lead.
Last season's runners-up Schalke were shocked 2-1 at home to Hanover, with defender Konstantin Rausch and striker Mohammed Abdellaoue scoring either side of half-time as the Royal Blues suffered their second consecutive defeat.
Hamburg had to come from behind to win 3-1 at Eintracht Frankfurt as Dutch defender Joris Mathijsen scored a 61st-minute equaliser to spare his side's blushes before Ruud van Nistelrooy claimed his third goal in two games.
Peruvian Jose Paolo Guerrero netted in the 89th minute to seal the three points for Hamburg.
Bremen bounced back from their hammering on the opening day of the season against Hoffenheim when they beat Cologne 4-1, while Freiburg beat Nuremberg 2-1 after coming from behind thanks to two goals by Senegal striker Demba Cisse.
On Friday, champions Bayern Munich suffered a shock upset when they lost 2-0 at 10-man Kaiserslautern.