Motherwell gained revenge for their Scottish Cup quarter-final defeat by Aberdeen thanks to Stevie Hammell's long-range thunderbolt.
Well must also beat Kilmarnock at Rugby Park next weekend to prevent Celtic being able to clinch the title away to Rangers the following day.
Hammell fired home from 35 yards after 22 minutes at Fir Park.
Aberdeen's Jason Brown was the busier goalkeeper, with Darren Randolph only called upon once to save.
And the deserved victory lifts Stuart McCall's side level with second-top Rangers, who were docked 10 points for going into administration but have a superior goal difference.
Defeat for the Dons on the same ground as last week's 2-1 Cup win ended their unbeaten run of 13 games in all competitions and leaves Craig Brown's side six points adrift of Hearts in the race to finish in the top half of the table before the Scottish Premier League splits into two.
Motherwell had been forced to hand Adam Cummins, 14 days after his 19th birthday, a debut in a defence decimated by suspensions for Shaun Hutchinson and Tim Clancy, plus captain Stephen Craigan's niggling injury.
Cummins' youth squad team-mate, Stuart Carswell, was given his second start in midfield against an Aberdeen side who were able to add the experience of Gavin Rae and Chris Clark.
It was the Dons who started in slightly more cohesive fashion, with the two managers switching their formations in an attempt to wrong-foot their counterpart in light of a familiarity resulting from last weekend's Cup meeting.
However, Aberdeen were fortunate that referee Iain Brines ruled that Andrew Considine was not the last man when the defender's hauling down of Henrik Ojamaa resulted in a yellow card instead of red.
The Estonian striker set up the opening goal soon after, his ball into the path of Hammell allowing the defender to fire high into the corner of the net from all of 35 yards.
Only an excellent save from Brown prevented Carswell scoring his first senior goal after Brines allowed play to progress after a foul by the already-booked Considine, who was testing the referee's patience.
Brown rescued the Dons again when Steve Jennings directed a header powerfullly towards the top corner.
Considine fired a couple of yards over as Aberdeen finally threatened the Motherwell goal just in time to beat the half-time whistle.
However, it was back with the home side in the ascendency immediately after the break when Carswell's low, 20-yard drive forced a save from Brown.
The Dons were struggling to create chances but had two in quick succession after Scott Vernon's side-footed effort forced Randolph to turn the ball over the crossbar and Rory Fallon headed just too high from the resulting corner.
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Live Text Commentary
Full Time The referee blows his whistle to end the game.90:00 +2:39
Darren Randolph takes the free kick.90:00 +2:39 Booking
Booking Rory McArdle shown a yellow card.90:00 +2:28
Rory McArdle challenges Robert McHugh unfairly and gives away a free kick.89:52
Tom Hateley fouled by Mark Reynolds, the ref awards a free kick. Free kick taken by Darren Randolph.86:28
Stewart Carswell fouled by Kari Arnason, the ref awards a free kick. Direct free kick taken by Darren Randolph.84:54
Effort from the edge of the area by Chris Humphrey goes wide of the right-hand upright.82:21
Peter Pawlett challenges Tom Hateley unfairly and gives away a free kick. Darren Randolph takes the free kick.82:05
Robert McHugh gives away a free kick for an unfair challenge on Rory McArdle. Free kick taken by Rory McArdle.81:19 Substitution
Substitution Henrik Ojamaa goes off and Robert McHugh comes on.81:04
Mohamed Chalali has an effort at goal from just outside the box which goes wide of the right-hand upright.76:06
Corner taken right-footed by Peter Pawlett to the near post, Kari Arnason takes a shot. Save by Darren Randolph.74:51
Outswinging corner taken by Peter Pawlett from the right by-line, Adam Cummins makes a clearance.74:00
Free kick taken by Mark Reynolds.74:00 Booking
Booking Caution for Tom Hateley.73:51
Free kick awarded for a foul by Tom Hateley on Peter Pawlett.73:08
Direct free kick taken by Tom Hateley.73:08 Booking
Booking Kari Arnason receives a caution.72:54
Kari Arnason gives away a free kick for an unfair challenge on Stewart Carswell.71:34
Shot from just outside the box by Mitchel Megginson goes over the crossbar.
Substitution Ryan Jack leaves the field to be replaced by Mohamed Chalali.68:02
Michael Higdon takes a shot. Blocked by Mark Reynolds.67:47
Chris Humphrey takes a brilliant shot. Jason Brown makes a brilliant save.64:34
Kari Arnason produces a shot on goal direct from the free kick.64:34 Booking
Booking Booking for Jonathan Page.64:25
Free kick awarded for a foul by Jonathan Page on Peter Pawlett.62:27 Substitution
Substitution Peter Pawlett joins the action as a substitute, replacing Clark Robertson.59:49 Substitution
Substitution Mitchel Megginson on for Rory Fallon.58:15
Free kick awarded for an unfair challenge on Stewart Carswell by Chris Clark. Tom Hateley takes the direct free kick.57:03
Corner taken right-footed by Gavin Rae from the right by-line, Rory Fallon produces a header from inside the area that goes over the bar.56:46
Scott Vernon takes a shot. Jason Brown makes a brilliant save.55:12
Michael Higdon fouled by Andrew Considine, the ref awards a free kick. Centre by Tom Hateley, Header from deep inside the area by Jonathan Page goes harmlessly over the crossbar.53:52
Andrew Considine fouled by Henrik Ojamaa, the ref awards a free kick. Rory McArdle takes the direct free kick.52:52
Effort from 25 yards by Kari Arnason. Jason Brown makes a comfortable save.51:50
Corner taken by Tom Hateley from the right by-line played to the near post, Michael Higdon gives away a free kick for an unfair challenge on Andrew Considine. Free kick taken by Jason Brown.50:14 Booking
Booking Booking for Clark Robertson.49:58
Effort on goal by Rory Fallon from inside the penalty area goes harmlessly over the bar.46:39
Stewart Carswell has an effort at goal from 20 yards. Jason Brown makes a fantastic save.45:01
The match restarts for the second half.45:00 +0:03 Half time
Half Time It is the end of the first-half.43:27
Corner taken by Clark Robertson from the left by-line, Andrew Considine produces a right-footed shot from inside the area that clears the bar.41:35
Foul by Rory Fallon on Adam Cummins, free kick awarded. Darren Randolph restarts play with the free kick.41:16
Chris Humphrey produces a cross, Steve Jennings takes a shot. Save by Jason Brown.39:17
Free kick awarded for a foul by Rory Fallon on Jonathan Page. Darren Randolph takes the direct free kick.37:42
Rory Fallon challenges Jonathan Page unfairly and gives away a free kick. Stevie Hammell takes the free kick.33:02
Rory Fallon concedes a free kick for a foul on Adam Cummins. Tom Hateley takes the free kick.32:06
Free kick awarded for an unfair challenge on Henrik Ojamaa by Andrew Considine. Stevie Hammell takes the free kick.29:24
Tom Hateley takes a outswinging corner from the right by-line to the near post, Gavin Rae makes a clearance.28:46
Free kick awarded for an unfair challenge on Mark Reynolds by Henrik Ojamaa. Jason Brown takes the direct free kick.28:31
Corner taken by Tom Hateley from the left by-line to the near post, Mark Reynolds manages to make a clearance.26:51
Kari Arnason gives away a free kick for an unfair challenge on Stewart Carswell. Direct free kick taken by Steve Jennings.26:11
Stewart Carswell takes a shot. Save made by Jason Brown.23:41
Outswinging corner taken by Tom Hateley.21:35
Assist by Tom Hateley.21:35 Goal scored
Goal! - Stevie Hammell - Motherwell 1 - 0 Aberdeen Goal scored by Stevie Hammell from outside the box to the top left corner of the goal. Motherwell 1-0 Aberdeen.19:43
Foul by Scott Vernon on Steve Jennings, free kick awarded. Darren Randolph takes the free kick.17:48
Free kick awarded for an unfair challenge on Tom Hateley by Chris Clark. Free kick taken by Tom Hateley.15:25
Free kick taken by Tom Hateley.15:25 Booking
Booking Andrew Considine is shown a yellow card for unsporting behaviour.15:16
Andrew Considine gives away a free kick for an unfair challenge on Henrik Ojamaa.13:48
Foul by Michael Higdon on Andrew Considine, free kick awarded. Jason Brown takes the free kick.13:07
Scott Vernon produces a right-footed shot from just outside the penalty box that misses to the left of the target.3:08
The official flags Scott Vernon offside. Darren Randolph takes the free kick.1:12
Shot by Gavin Rae from just outside the area goes over the net.0:11
Stewart Carswell fouled by Rory Fallon, the ref awards a free kick. Direct free kick taken by Darren Randolph.0:00
The match has kicked off.
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