Borussia Dortmund's miserable season hit a new low as they threw away a 4-0 half-time lead to draw 4-4 at home to derby rivals Schalke.
Dortmund, with just one point from their last five Bundesliga games and out of the Champions League, blew away their in-form visitors with four goals in the opening 25 minutes, including three in eight minutes.
Pierre-Emerick Aubameyang opened the scoring after 12 minutes and, after Benjamin Stambouli diverted a free kick into his own net, further goals from Mario Gotze and Raphael Guerreiro left both sets of fans inside Signal Iduna Park rubbing their eyes in disbelief.
That feeling only increased after the break, though, as Dortmund's fragile confidence was shattered.
Guido Burgstaller and substitute Amine Harit pulled goals back and, after Aubameyang was sent off for a second booking, Daniel Caligiuri's fine goal in the 86th minute set up a grandstand finale.
Seven minutes of added time frayed Dortmund nerves yet further and they caved in four minutes in when Naldo, who had earlier had a goal ruled out by the video assistant referee, headed the equaliser.
The hosts had gone into the match on such a terrible run of form questions were already being asked of head coach Peter Bosz.
Schalke in contrast had won four and drawn one of their five, keeping four clean sheets, to start the weekend second in the table.
But this was the day for Dortmund to release all their pent-up anger and frustration -- only to see it return in abundance.
Aubameyang, banned by the club for the 2-1 defeat to Stuttgart in their last league game for unexplained 'disciplinary reasons', started the rout by sliding in at the far post to turn home a mis-hit shot from Nuri Sahin.
Sahin created the second too, although this time rather more deliberately, as his deep, inswinging free-kick from the right caused chaos in the Schalke defence and Stambouli, in trying to cut it out, only stabbed it past his own goalkeeper Ralf Fahrmann.
That goal came in the 18th minute and two minutes later Gotze made it three.
Aubameyang raced down the right before crossing for his team-mate to head home at the far post.
Guerreiro slammed home number four five minutes later, connecting with the sweetly-struck left-foot volley after the ball dropped to him in the area.
Schalke boss Domenico Tedesco responded by making a double substitution in the 33rd minute, withdrawing Franco Di Santo and Weston McKennie for Leon Goretzka and Harit.
But Tedesco's mood will have darkened their further eight minutes into the second half when Naldo headed home, only for VAR to disallow the goal off for offside.
Schalke instead got one back through Burgstaller in the 61st minute, the striker looping a header over Roman Weidenfeller in the Dortmund goal from a Stambouli long ball.
The visitors had a second four minutes later. Dortmund were far too slack at the back, allowing Harit time to bring down Yevhen Konoplyanka's cross from the left and drive home.
Aubameyang's foul on Harit earned the striker his marching orders after 72 minutes and shortly after Gotze was forced off by injury.
The hosts were rocking badly and conceded again when Caligiuri cut inside from the right and fired into the top corner. And Dortmund's despair was complete when Naldo rose highest to meet Konoplyanka's corner.