Bundesliga basement boys Karlsruhe ended a nine-match winless run to reignite their hopes of survival.
Sebastian Langkamp scored the only goal at Bayer Leverkusen in the 72nd minute with a bizarre long-range effort which left home goalkeeper Rene Adler embarrassed.
The result was not enough to lift Edmund Becker's men off the bottom of the table, but did take them to within two points of 15th-placed Arminia Bielefeld, who travel to Borussia Monchengladbach tomorrow.
Both sides created chances in an even opening, but it was Leverkusen who threatened first, Patrick Helmes receiving the ball from Simon Rolfes but firing into the side netting from a tight angle.
At the other end, Christian Eichner crossed to the middle of the area for Sebastian Freis, who volleyed wide of the right-hand post.
Leverkusen began to take control of the game and almost went ahead in the 20th minute as Renato Augusto put Arturo Vidal through one on one with Karlsruhe keeper Markus Miller.
Vidal shot low left footed, but Miller did well to tip the ball round the post.
Leverkusen dominated possession either side but struggled to create chances.
And it was the visitors who took the lead, albeit in unconventional fashion.
Langkamp brought the ball out of defence and into the centre circle, before hoofing the ball high into the Leverkusen half.
The defender was not attempting a shot, but somehow the ball sailed over Adler, who was not a long way off his line, and nestled in the back of the net.
Leverkusen, who perhaps had their minds on other things after reaching the DFB-Pokal final in midweek, started to get frustrated as still they struggled to find a way through.
Their best chance came in the 76th minute when Sascha Dum advanced into the box and crossed for fellow substitute Angelos Charisteas, who could not get a shot in before the ball was cleared for a corner.