Aberdeen suffered their worst ever European result
Aberdeen fell to a humiliating first leg defeat at home to Sigma Olomouc in the Europa League qualifier, first leg.
The Czech visitors started impressively and Michal Hubnik put them into an 18th-minute lead from close range.
Charlie Mulgrew levelled soon after with a tremendous curling free-kick but Lukas Bajer also found the net with a similar set-piece on 65 minutes.
Jakub Petr, Michal Ordos and Tomas Horava then cracked in fine strikes as the Dons fell apart.
In what was manager Mark McGhee's first match in charge at Pittodrie, the early mood of optimism among home fans gave way to despondency over the course of the evening and the team trudged off to an angry chorus of boos.
Aberdeen responded well to losing an early goal and Richard Foster flashed a header narrowly wide before Mulgrew's excellent equaliser but they posed almost no threat thereafter.
With McGhee's team flagging in the second half and frequently losing possession, the Czechs capitalised with some fine finishing and could have added to their handsome tally.
The Dons had an unfamiliar look about them, with Stuart Duff deputising for the injured Zander Diamond in the centre of defence and midfielder Derek Young starting the match at right-back.
And the makeshift defence were given a torrid time by the visiting team, who are only one game into their domestic season.
Young's inexperience in his new position was almost costly after 11 minutes when he allowed Hubnik too much space but Tomas Janotka was unable to connect with his low driven cross with the goal gaping.
The opener came when Hubnik reacted quickest to turn the ball home after Jamie Langfield had parried Janotka's header from a Rudolf Otepka corner.
The Dons should have equalised a minute later when Sone Aluko crossed for the unmarked Foster but the defender missed the target from close range.
But McGhee's men restored parity in spectacular fashion moments later courtesy of a dipping free-kick from dead-ball specialist Mulgrew from 25 yards.
Petr Drobisz then denied Mulgrew a second goal from a set-piece with a fine save seven minutes after the break.
Petr should have restored Olomouc's lead on the hour but the striker volleyed the ball over the crossbar from a near-post Bajer corner.
Bajer later curled a delicious free-kick into the net from 25 yards and soon after Hubnik released Petr, who expertly drilled the ball past Langfield.
Ordos added a fourth with an angled drive and Horova rounded off the scoring in the dying stages with a low drive after pouncing on a careless Duff mistake.
No Scottish team has ever recovered from a four-goal deficit in European competition.
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