Scott Vernon broke his 2014 goalscoring duck with a hat-trick that leaves Aberdeen clear favourites to clinch second place in the Scottish Premiership.
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Vernon grabbed an opportunity presented by Adam Rooney's ankle injury to send the Dons four points above Motherwell thanks to a 3-1 victory over a much-changed Dundee United at Tannadice.
The striker netted his first goal since December when he slotted home from 10 yards in the seventh minute but United hit back when defender Sean Dillon netted with a powerful deflected strike.
Aberdeen goalkeeper Jamie Langfield made brilliant saves from Andy Robertson and Mark Wilson before Vernon nodded home 10 minutes into the second half after goalkeeper Marc McCallum had lost Barry Robson's corner.
United pressed again but a mistake by Gavin Gunning allowed Vernon to complete his treble with 15 minutes left.
The result assures Motherwell of a Europa League place with United now needing to beat St Johnstone in the William Hill Scottish Cup final to qualify.
However, with the Dons 14 goals better off than Motherwell, it leaves Stuart McCall's side needing to beat Inverness at Fir Park on Wednesday and Aberdeen at Pittodrie on Sunday to finish second.
United made six changes with the ill Gary Mackay-Steven dropping out and Paul Paton and John Rankin sidelined by knocks. McCallum made his debut while Brian Graham, Morgaro Gomis and Wilson started.
United had a penalty appeal rejected when Ryan Dow fell under the challenge of Russell Anderson and Aberdeen soon took the lead when the home defence parted wide open as Peter Pawlett cut in from the right channel. Vernon took over and slotted home.
Nadir Ciftci almost hit back when he burst away from two men and fired a powerful left-footed shot from 20 yards that Langfield dived to turn away.
Pawlett set up Vernon again but this chance was further out and on the striker's left foot and he sliced high and wide. Barry Robson then rose well to meet Niall McGinn's cross but headed just wide.
Aberdeen looked comfortable but they lost Willo Flood in the 31st minute when he pulled a thigh muscle. Cammy Smith came on.
United were level three minutes later. Stuart Armstrong took down a deep cross from Ciftci on the right edge of the box and laid it back in the direction of Dillon, who fired a powerful shot that nicked off Mark Reynolds and flew into the roof of the net.
Robertson soon met Dow's right-wing cross on the volley to guide a shot towards the far corner, but Langfield threw himself to his left to tip the ball wide.
The hosts nearly scored again from a similar move, this time Langfield pushing Wilson's volley on to the bar following Ciftci's centre.
Dons left-back Jonny Hayes produced a crucial clearance just after the restart and the visitors had a goal disallowed for offside when McGinn stooped to head home after McCallum spilled Smith's strike.
Gunning claimed he was pulled by Anderson in the other box and Robertson shot over before McCallum blocked from Vernon at close range after being troubled by Hayes' deep cross.
The debutant was beaten by Robson's delivery from the resulting corner and Vernon nodded home from a yard out.
Ciftci had an instant chance to level when Armstrong's cross found him unmarked at the back post but he tried to burst the net and blazed over instead.
Dow was flagged offside as he turned home Graham's return pass and Langfield made another point-blank save to stop Graham turning home Ciftci's wonderful low cross.
Aberdeen brought on defender Alan Tate for McGinn and moved to a five-man defence and they went further ahead moments later.
Gunning missed his header from Langfield's long free-kick and Vernon ran through, rounded the goalkeeper and slid the ball into the net.