Hoffenheim secured their first win over Bayern Munich on Tuesday, as Andrej Kramaric's goal secured a deserved 1-0 triumph over the Bundesliga leaders at the Rhein-Neckar-Arena.
Kramaric's long-range strike midway through the first half proved enough for Hoffenheim to break their duck against the below-par champions at the 18th attempt.
Julian Nagelsmann's side - who had led in the reverse fixture at the Allianz Arena last November before having to settle for a 1-1 draw - are now unbeaten in seven games but remain third in the table, a point behind second-placed RB Leipzig, who travel to Mainz on Wednesday.
Robert Lewandowski hit the woodwork in the first half but the visitors saw their 20-match unbeaten streak in all competitions come to a tame end, the defeat just their third in an otherwise excellent season.
While the result seems unlikely to stop their inexorable march towards a record fifth successive title, it is hardly ideal so early in a massive month that includes two meetings with Borussia Dortmund, as well as a Champions League quarter-final tie against Real Madrid.
Carlo Ancelotti's runaway leaders had not conceded in their last five league outings, yet could have easily been 3-0 down by the time Kramaric's thumping strike gave the hosts a deserved lead after 21 minutes.
The former Leicester City striker followed up his brace in Saturday's 3-1 win at Hertha Berlin with a powerful strike that Sven Ulreich, still standing in for the injured Manuel Neuer in Bayern's goal, failed to keep out despite getting a strong hand to the ball.
Denied as early as the second minute by a wonderful block from covering full-back Rafinha, Kramaric had already gone close with a low drive before Nadiem Amiri shot straight at Ulreich when presented with a glorious one-on-one opportunity.
Bayern needed their back-up goalkeeper to keep the deficit down to one before the break, a reactionary save stopping Kerem Demirbay converting Kramaric's through ball.
Yet despite struggling in attack, the visitors were denied an equaliser in stoppage time when Lewandowski turned Kingsley Coman's cross against the bar.
Despite a plethora of attacking options on his bench, Bayern coach Ancelotti kept faith with the starting XI at the start of the second half.
Lewandowski looked to have engineered an equaliser 10 minutes after the interval, only for his right-footed shot from the edge of the penalty area to be tipped wide by the diving Oliver Baumann.
Coman then poked wide under pressure from the Hoffenheim goalkeeper as Bayern began to assert their authority, although Kramaric blazed over when presented with a rare opportunity to double both his and Hoffenheim's tally.
Franck Ribery was brought on and nearly conjured an equaliser within two minutes of his introduction, the Frenchman's toe-poked effort out of nothing forcing Baumann into action.
Lewandowski also had a late attempt deflected wide in a nervy finish, but Hoffenheim held firm to clinch a famous victory.