Daizen Maeda handed Celtic a Europa Conference League lifeline after his goal gave the hosts something to cling to in a dismal 3-1 first-leg defeat against Bodo/Glimt in the play-offs.
Goals from Runar Espejord, Amahl Pellegrino and Hugo Vetlesen left the Scottish Premiership leaders reeling, as Kjetil Knutsen's side seized the advantage in Glasgow.
On the back of their Europa League exit last December, Ange Postecoglou's hosts headed into the inaugural edition of UEFA's newest competition looking to deliver a positive result.
Yet they were rattled early on by the Eliteserien champions, who struck inside the first six minutes when Espejord turned Joe Hart the wrong way with a low close-range strike.
Celtic's subsequent struggle to click in the final third left them labouring for a response before the break, and an arguably lenient booking for a Pellegrino foul further frustrated their players.
The winger wasted little time after the restart to make the most of a potential escape, too, when he latched onto Espejord's flick to tuck another close-range finish into the net.
The arrival of Reo Hatate just beyond the hour mark saw Postecoglou's side find a fresh burst of life, and when Maeda cut the gap with a fine header, it looked like they had a chance to rally.
But the visitors promptly responded through Vetlesen's deflected 20-yard strike to put any comeback to bed, taking a crucial upper hand into next week's return fixture as they look to push on to the last 16.
What does it mean? Celtic at risk of successive knockout blows
Having dropped into the third tier of European football after a third-place Europa League group-stage finish, the Bhoys welcomed their visitors with the hope of a statement result in response.
Yet with nothing to show for their lacklustre efforts on a cold February night in Glasgow, they now find themselves facing the prospect of back-to-back European eliminations.
Despite their domestic dominance this term, Postecoglou's side have failed to fully convince in two competitions now – and unless they muster a major response, they face another immediate exit.
Hosts pay for wasted opportunity
With 57 clocked up this term across 26 games in the Scottish Premiership, Celtic have not typically wanted for goals.
But with just six shots on target from 15 attempts and just 1.3 expected goals, they were made to suffer for their lack of clarity in front of the net against their Norwegian rivals.
Bodo/Glimt display ruthless edge
Having now gone 10 European games without defeat, Bodo continue to prove themselves among the neutral's favourites following another fine display.
If not as flamboyantly smash-and-grab as their 6-1 blowout against Roma, their three-goal haul nevertheless thrilled their supporters – and with just four shots on target all game, they showed a clear ruthless edge to seize the advantage.
What's next?
Celtic return to domestic action in the Scottish Premiership, welcoming Dundee to Celtic Park, while Bodo/Glimt will bide their time for the reverse last-16 clash back home in Norway next week.