Celtic's hopes of reaching the Champions League proper were left in ruins after a jaw-dropping second-leg defeat to LASK, as the Austrian side overturned a four-goal aggregate deficit to win 5-4 after extra time in Linz.
The Scottish champions appeared to be cruising through to the next stage when captain Callum McGregor's deflected effort put them 4-0 up on aggregate after just 21 minutes, sparking celebratory chants of "we're having a party in the Champions League" among the travelling support. What followed, however, was one of the most dramatic collapses in the club's recent European history.
LASK hit back almost immediately when Moses Usor coolly converted after being played through by Benjamin Nygren, a finish former Scotland striker James McFadden described on BBC Radio Scotland as "an absolute gift" for the hosts, given how the chance was created.
The home side's momentum built rapidly after the interval. Robert Ljubicic was given far too much space on the edge of the box and drilled a low shot beyond goalkeeper Viljami Sinisalo to put LASK ahead on the night. McFadden was scathing of the Celtic defending that allowed the chance, branding it "unacceptable" after Auston Trusty failed to close down the midfielder.
Celtic's afternoon went from bad to worse as Samuel Adeniran curled in a stunning 25-yard strike after good build-up play from Sascha Horvath, cutting the aggregate lead to just one goal. By this stage, Celtic were struggling to string passes together and were pinned back for long spells as LASK dominated possession and territory.
The hosts continued to press for the goal that would complete their comeback within normal time, striking the woodwork and forcing a smart save from Sinisalo to deny Alemao. But it was Florian Flecker who eventually found the net, heading home in stoppage time after Alemao's initial header was parried, leveling the aggregate score at 4-4 and forcing extra time.
There was to be no respite for Celtic. With just over ten minutes remaining in the additional period, Luke McCowan was dispossessed after a hesitant decision in midfield, and Adeniran punished the mistake with another fine strike from distance to make it 5-4 on aggregate. Sinisalo did deny Adeniran a hat-trick by saving a late penalty, but the damage had already been done, and LASK held on to seal a historic victory.
The result draws uncomfortable parallels with Celtic's Champions League qualifying exit to Kairat Almaty at the same stage last season, a defeat that fans and pundits alike felt cast a shadow over the remainder of that campaign.
Former Celtic manager Neil Lennon, speaking to Amazon Prime, did not hold back in his assessment of the team's physical and mental state. "It looked to me as if Celtic were exhausted," he said. "Fragile in duels. It only looked like there would be one winner. Huge credit to LASK. They battered Celtic tonight, physically and on the football side. It could have been more."
The defeat represents a major setback for Celtic's European ambitions and will prompt serious questions about the club's resilience and depth after squandering what had seemed an unassailable advantage. LASK, by contrast, will celebrate one of the most memorable European comebacks in recent memory as they progress at Celtic's expense.
Based on reporting from BBC Sport.