Match ends, Motherwell 2, Aberdeen 1.
Aberdeen slipped four points behind Premiership leaders Celtic as they lost a lead and ended with 10 men against resurgent Motherwell at Fir Park.
Aberdeen's Kenny McLean converted a penalty on the stroke of half-time.
Scott McDonald levelled with an opportunistic header and Louis Moult made it two in two minutes when he clipped the ball beyond Scott Brown.
The Dons then had Barry Robson sent off for elbowing McDonald moments after coming off the bench.
It has been a remarkable week at Fir Park, ending with a fifth win in six matches for the Steelmen.
Before kick-off there was bad news for the hosts when it emerged that James McFadden, whose season has been peppered by dreadful luck, had broken his ankle in training.
And Mark McGhee confessed the former Scotland star would have started in a line-up which showed three changes after a midweek virus had threatened to tear the manager's plans apart.
Aberdeen did everything but score in the opening spell in the glorious Lanarkshire sunshine, with Connor Ripley saving well from Dons skipper Ryan Jack and Simon Church pulling a shot wide, while McLean should have hit the target with a free header.
Motherwell's first real effort arrived after 21 minutes and it was beautifully engineered. Moult's cross was taken first time on the half volley by Marvin Johnson and the ball only just cleared the crossbar.
Moult then rattled Brown's right hand post after a headed lay-off from McDonald.
But the decisive period of the half came on 44 minutes after Motherwell were denied a free kick for a foul on Johnson right in front of the home dug-out. Referee Don Roberston waved play on and, following a sequence of fizzing passes, Jonny Hayes broke into the box only to be floored by Kieran Kennedy.
McLean scored from the penalty spot and as the teams left the pitch at half-time a clearly furious McGhee and Johnson waited to confront the official about the absence of a foul in their favour.
But the hosts' fury turned to delight after a spirited comeback in the second period.
Ripley was at full-stretch to push away a fierce McLean strike and an improvised overhead kick from Church grazed the crossbar as Aberdeen threatened on the break.
But McDonald, who once famously denied Celtic a title in a Motherwell jersey, this time did the champions a favour when he finished a game of head tennis with a looping equaliser on 72 minutes.
Moult then stunned the title hopefuls with a cute lob, taking advantage of a mix up between Mark Reynolds and goalkeeper Brown.
Aberdeen's afternoon got even worse when substitute Robson was red carded after catching McDonald with a leading elbow and there was no way back for the 10 men.
- 16KennedyBooked at 44mins
- 26CaddenSubstituted forAinsworthat 49'minutes
- 21LeitchBooked at 51mins
- 17GomisBooked at 34mins
- 20MoultSubstituted forFletcherat 87'minutes
- 4ConsidineSubstituted forRobsonat 78'minutesBooked at 79mins
- Don Robertson
- Shots on Target
Second Half ends, Motherwell 2, Aberdeen 1.
Shaleum Logan (Aberdeen) wins a free kick in the defensive half.
Foul by Marvin Johnson (Motherwell).
Attempt blocked. Marvin Johnson (Motherwell) right footed shot from the centre of the box is blocked.
Attempt saved. Simon Church (Aberdeen) right footed shot from the centre of the box is saved in the centre of the goal.
Attempt saved. Wes Fletcher (Motherwell) left footed shot from the centre of the box is saved in the top centre of the goal.
Substitution, Motherwell. Wes Fletcher replaces Louis Moult.
Attempt missed. Lionel Ainsworth (Motherwell) left footed shot from the right side of the box is close, but misses to the right.
Attempt saved. Jonny Hayes (Aberdeen) left footed shot from outside the box is saved in the bottom left corner.
Foul by Morgaro Gomis (Motherwell).
Jonny Hayes (Aberdeen) wins a free kick in the defensive half.
Foul by Louis Moult (Motherwell).
Mark Reynolds (Aberdeen) wins a free kick in the defensive half.
Corner, Motherwell. Conceded by Ash Taylor.
Barry Robson (Aberdeen) is shown the red card for violent conduct.
Scott McDonald (Motherwell) wins a free kick in the defensive half.
Foul by Barry Robson (Aberdeen).
Substitution, Aberdeen. Barry Robson replaces Andrew Considine.
Goal! Motherwell 2, Aberdeen 1. Louis Moult (Motherwell) right footed shot from the centre of the box to the high centre of the goal. Assisted by Steven Hammell.