Borussia Dortmund suffered a shock 3-0 league defeat at Bundesliga strugglers Hamburg on Saturday, just three days before their Champions League last-16 clash away to Zenit St Petersburg.
Jurgen Klopp's Dortmund got the worst possible result ahead of their trip to Russia for Tuesday's first-leg clash while Hamburg recorded their first league win since November in Mirko Slomka's first match in charge as coach.
Hamburg are in danger of being relegated from the Bundesliga for the first time in their history and sacked coach Bert van Marwijk last Saturday -- after only 143 days in charge -- in the wake of their 4-2 drubbing at bottom side Eintracht Braunschweig.
His successor Slomka signed a two-year deal on Monday and enjoyed a winning debut as his side broke their eight-match losing streak, including a club record seven league matches.
"That is just one of 13 games and we won't stop working," said Slomka.
"We didn't quite deserve to win by that margin, but we did well in defence and the team can be proud of the points."
The 46-year-old Slomka punched the air as left winger Petr Jiracek gave Hamburg the lead three minutes before the break after a superb cross from striker Pierre-Michel Lasogga.
The 22-year-old Lasogga, on loan from Hertha Berlin, then added the second when he darted on to a defence-splitting pass from defensive midfielder Tolgay Arslan on 58 minutes to net his 11th of the season.
Turkey midfielder Hakan Calhanoglu then sealed Hamburg's three points when he fired home a 91st-minute free kick.
The result lifts Hamburg up to 16th, but still amongst the bottom three relegation places, while Dortmund stay third.
"That was a modest performance by us," said Klopp, whose team suffered their sixth defeat in eight league games in Hamburg.
"We imploded at times, it was brutal to watch."
There was more bad news for the pack chasing runaway league leaders Bayern Munich as second-placed Bayer Leverkusen went down 3-1 at VfL Wolfsburg, meaning Sami Hyypia's side has lost seven of their last nine games.
Leverkusen suffered a Champions League hangover, following their 4-0 last-16, first-leg home defeat to Paris Saint-Germain, with another poor display.
Dutch striker Bas Dost put Wolfsburg ahead and while Germany winger Sidney Sam equalised for Leverkusen on the stroke of half-time, Wolves' Brazil midfielder Luiz Gustavo netted their second with half an hour to play.
Left-back Ricardo Rodriguez then scored from a penalty at the second attempt with 17 minutes from time, tapping home the rebound after Leverkusen goalkeeper Bernd Leno had saved the initial spot-kick to leave Wolves fifth in the league.
European champions Bayern are at Hanover 96 on Sunday evening looking to build on their commanding 16-point lead and extend their record 46-match unbeaten league run.
Results on Saturday means the three teams behind the Bavarian giants -- Leverkusen, Dortmund and Schalke -- picked up just one point between them and Guardiola's side can finish the weekend 19-points clear.
Braunschweig are now three points adrift at the bottom after their 2-1 defeat at ten-man Nuremberg in a match where three penalties were saved.
Borussia Moenchengladbach stay sixth, but are winless in their last seven games after their 2-2 draw at home to Hoffenheim.
Augsburg got back to winning ways with a 4-2 victory at Freiburg to bounce back from last weekend's defeat to Nuremberg, their only loss in the last eight games.
VfB Stuttgart are just above the bottom three after they suffered their seventh straight defeat at home to Hertha Berlin, who ran out 2-1 winners.
Hertha's replacement striker Sandro Wagner headed the winner, three minutes from time, but was then sent off for a second yellow card having only been on the pitch for 12 minutes.
Fourth-placed Schalke, who host Real Madrid in Wednesday's Champions League last-16, first-leg clash, stayed fourth after their goalless draw at home to Mainz 05 on Friday.