Aberdeen's Arild Stavrum dumped Dundee United back into the Scottish Premier Division relegation mire with his second hat-trick in six weeks at Pittodrie.
The Dons striker grabbed two goals in the first half, made a third for Derek Young and added another late on to halt the Tangerines' recent impressive run.
Most of the action came in the opening period and though the visitors fought hard to claw their way back into the game after the interval they were unable to break down a resolute Aberdeen defence.
The defeat leaves United just three points ahead of basement side St Mirren with six games of the campaign remaining.
And with Livingston striding back to the top of the First Division last night the battle to avoid the drop seems set to go right to the wire.
Fresh from their remarkable win at Ibrox on Saturday the Tangerines travelled north expecting to extend a record which had seen them lose only one game since the turn of the year.
Aberdeen, without a win in their last three outings, had seen their top-six hopes extinguished with defeat by Celtic on Sunday but were keen to prove that improvement had been made following their basement finish last term.
And in an entertaining, open contest which made excellent viewing from the start the Dons were in front within five minutes.
Stavrum held off Jason de Vos inside the visitors' box to reach David Rowson's through ball and produced a thunderbolt strike which whipped past goalkeeper Paul Gallacher and into the top corner.
The Norwegian, clearly scenting goals, almost slid home a Derek Young cross-shot shortly afterwards.
After finishing last season as top scorer with 12 league strikes to his name Stavrum initially struggled to recapture that form this term.
But a hat-trick against St Mirren at the end of February put him into double figures for the season and just before the half-hour mark he equalled last campaign's tally when he arrived with perfect timing at the near post to nod home Robbie Winters' curling free-kick.
The goal put Aberdeen ahead for a second time, Danny Griffin pegging back Stavrum's original strike with a brilliant free-kick which swerved in from the edge of the area after Thomas Solberg had bundled over Charlie Miller.
By this time the Dons had also lost Rachid Belabed - one of three new faces from Sunday's defeat - who departed through injury in bizarre circumstances.
The Moroccan appeared set to crunch Derek Lilley on the near touchline but the Tannadice front-man saw the tackle coming and caught Belabed with his own two-footed challenge.
Lilley was fortunate to escape a booking from referee John Fleming and Belabed limped on before Ebbe Skovdahl eventually decided to replace him.
As Andy Dow made his way onto the field Belabed began a prolonged verbal assault on Fleming, earning himself a caution.
The punishment could have been even worse as the midfielder continued his tirade but David Rowson managed to intervene and pushed his team-mate towards the dug-out, where he was forcibly escorted down the touchline and into the tunnel by a member of the Dons back-room staff.
As if Belabed's antics were not enough, Aberdeen grabbed another before the break when Stavrum drove a shot against Gallacher. The ball looped off the United keeper and spun wickedly away from Griffin and Derek Young had the easiest of tasks to smash into an empty net.
By first-half standards the second period was a mundane affair.
David Hannah replaced Paul Robinson as United boss Alex Smith tried to freshen up his team and it worked to an extent as the visitors began to dominate.
But generally the Aberdeen defence stood firm and though Steven Thompson beat the offside trap to pull an inviting cross back for Miller the former Rangers man could only rattle the crossbar.
And as United pushed forward furiously Aberdeen cruelly waited to pick them off.
With the clock ticking down substitute Darren Mackie found acres of space on the right wing and his far-post ball ran invitingly into Stavrum's path and the striker calmly slotted home.