Dundee United clinched a European place after leapfrogging Aberdeen into fourth place in the William Hill Premiership with a stunning 2-1 comeback win.

Danish attacker Jeppe Okkels scored his first goal for the Dons since signing on loan from Preston in January after 15 minutes with the visitors controlling the game.

United gradually came back into it and in the 56th minute defender Declan Gallagher levelled with a header from a Glenn Middleton corner.

Striker Sam Dalby put United ahead with a penalty in the 62nd minute and when the dust settled on the final day of top-six fixtures – and there was an unseemly pitch invasion by home fans at the final whistle – Jim Goodwin’s men, back in the top flight this season, finished fourth which brings a potential Europe League qualifying place.

Aberdeen are able to swipe it back if they win the Scottish Cup against Celtic next week, albeit the champions failing at the last hurdle of another domestic treble is a long-odds prospect.

St Mirren fought out a commendable 1-1 draw with Celtic at Parkhead but that was not enough to prevent them finishing sixth.

Both sides went into the game struggling for form.

The Taysiders had suffered four successive post-split defeats while Aberdeen had lost their last three games, including a 5-1 thrashing at Celtic.

Jimmy Thelin’s side, though, had secured European football before the game and they had the first real effort on goal in the seventh minute with United keeper Dave Richards turning a 20-yard drive from Pape Gueye past the post.

As the Dons kept the home side penned inside the box from the corner, midfielder Jamie McGrath smacked the bar with a shot but United survived the subsequent scramble.

But Aberdeen soon went ahead when midfielder Leighton Clarkson sent captain Graeme Shinnie racing down the left with his cross initially defended by Richards and Gallagher close to the goalline.

Alexander Jensen picked up the loose ball, however, and cut it back for Okkels to lift the ball high into the net from 10 yards.

The lacklustre visitors gradually worked their way back and in the 39th minute Aberdeen keeper Dimitar Mitov made a decent save from Sam Cleall-Harding’s drive from distance, before Vicko Sevelj’s cross was headed just past the post by Dalby.

Within minutes of the restart United’s Kristijan Trapanovski headed a cross from Will Ferry into the ground and over the bar from six yards.

At the other end, Scotland striker Kevin Nisbet took an incisive pass from Clarkson and with time and space curled a shot over the bar when he ought to have at least hit the target.

The home side stepped it up and forced a series of corners and eventually Gallagher leapt inside a packed six-yard box to head in.

Then referee John Beaton pointed to the spot when Ryan Strain was fouled in the box by Okkels amid heavy Terrors’ pressure and Dalby sent Mitov the wrong way with his spot-kick.

The momentum of the game had swung completely and Mitov, after a poor kick to Dalby, had to block an effort from substitute Louis Moult.