St Mirren's European dream came to a painful end at Pittodrie after a damaging 3-0 defeat at the hands of Aberdeen.
The Buddies travelled to Pittodrie last night knowing a win could have potentially seen them leapfrog Hibs into fourth spot.
But a poor first half saw the Buddies trailing by two at half-time, Leighton Clarkson's free-kick breaking the deadlock before Graeme Shinnie nodded the hosts further in front.
The goals sandwiched a reckless red card for Saints defender Thierry Small, his second dismissal in four appearances, for a terrible tackle on Bojan Miovski that saw the Dons defender leave on a stretcher.
Shinnie rubbed salt in the wounds early in the second half when he bagged his brace with a cool finish that effectively put the result to bed.
The defeat left the Paisley club relying on Celtic doing them a favour by beating Hibs at Easter Road, meaning Stephen Robinson's side would have remained just two points behind the capital club who sit in fifth.
But Lee Johnson's men staged a comeback 4-2 win against the 10-man champions in Leith, leaving the Buddies in sixth spot whatever their result against Rangers this Saturday.
Curtis Main crucially passed a late fitness test to lead the line for the visitors, with strike partner Alex Greive missing out altogether.
Aberdeen were boosted by the return of three key players, with Duk Lopes and Ross McCrorie back from injury and skipper Shinnie available after a four-game suspension.
Ryan Strain threaded a ball through in the early stages that almost slipped Main in one-on-one. Dons keeper Kelle Roos was quick off his line to snuff out the danger.
After a quiet opening quarter of an hour a misplaced Greg Kiltie pass sent Jonny Hayes tearing through on goal. The midfielder then barged the winger over to hand the Dons a free-kick in a very promising position.
That foul was to prove costly, with Liverpool loanee Clarkson stepping up to curl a sweet effort past Trevor Carson to break the deadlock.
Shinnie blasted over the bar two minutes later as Aberdeen threatened to extend their lead and give Robinson's men a mountain to climb.
A pinpoint pass from Baccus found Small on the left wing as St Mirren looked to fashion a response. The teenager delivered a deft cross into the box, with Alex Gogic's header drawing a fine save from Roos who tipped over the bar.
From the resulting corner, Gogic escaped his marker and powered another header just wide of the post as the Saints started to grow into the game.
On the half hour mark a tough task got even more difficult when Small rashly brought down Bojan Miovski on the right wing.
Referee Don Robertson initially flashed a yellow but, after seeing the incident back when called over by VAR, the card was rightly upgraded to a red with the Aberdeen striker forced off injured.
The Dons immediately had a lot more space to play with, breaking forward whenever they could on the depleted St Mirren backline.
Carson denied Duk on a dangerous breakaway, before jumping straight back on his feet to deny sub Marley Watkins just two seconds later.
O'Hara pinged a header well over the bar as the Buddies tried to find a way back into the game.
It was the Dons that made their mark on the scoresheet again though. Lively Watkins burst down the flank, seizing on a mistake by Richard Taylor, before sending in a wicked cross that deflected goalwards off Joe Shaughnessy.
Carson produced a brilliant reflex save, but unfortunately for the Buddies the ball bounced straight to Shinnie - who looped a header into the far corner to double the hosts' lead.
Robinson turned to his bench as he looked to turn the unlikely tide, with youngster Kieran Offord and wing back Scott Tanser replacing Baccus and Richard Taylor at the break.
But just five minutes into the second half the home side put the result beyond all doubt.
Duk's clever pass down the wing sent Watkins racing down the right wing and into the box.
His clever cut-back found Shinnie, who calmly collected before slotting past Carson to bag his second of the match and put the Dons in cruise control.
The Buddies were fighting a losing battle but refused the throw in the towel without a fight.
Strain tried to claw one back with a trademark free-kick on the hour mark, The Aussie's curling low effort was well-saved by Roos.
Main had a brilliant chance to keep up his scoring record against his former employers when he latched on to a clever ball over the top by Gogic.
Aberdeen keeper Roos stood up well to deny the forward, much to the delight of the home support.
Watkins slammed a late effort inches wide of the post with Carson beaten as the home side cruised to all three points that, coupled with Hibs win against Celtic, extinguished the Saints dreams of European football next season.
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