Celtic's momentum under interim boss Martin O'Neill came to a shuddering halt as Europa League leaders Midtjylland taught them a lesson in eight dreadful first-half minutes in Denmark.

The 73-year-old, who had overseen two wins since replacing Brendan Rodgers at the Scottish champions, was under no illusions of the scale of the challenge facing his rejuvenated side, with the Danes already having defeated Nottingham Forrest.

No matter how prepared he thought he was, O'Neill - along with many others – must have been blown away by the ferocious first half from the hosts.

By the time Martin Erlic nodded in the opener, Midtjylland could have been out of sight, such was their dominance.

Their deserved advantage was doubled within two minutes as Mikel Kruger-Johnsen escaped the attentions of the Celtic defence and sumptuously lifted a stunning finish into the far corner of the net.

Shocked, spooked and then static, Celtic stood like statues as the fantastic Franculino Dju fired in a third before the break.

The second-half assignment was one of damage limitation, and though the scoreline suggested that mission was accomplished, it was a mystery how Midtjylland didn't score more goals.

Instead, out of nowhere, Celtic clawed one back as Callum Osmand - who later left the pitch on a stretcher - was felled by Erlic with 10 minutes remaining.

Reo Hatate's smart penalty sparked something within the visiting ranks, but as has been the issue, long before O'Neill's return, it was too little, too late.

And it leaves Celtic outside the qualification places for the knockout stage of the competition at the halfway point.

An outclassed Celtic did well to escape with just the three goals against, such was the utter dominance of the Danes.

Twenty-four shots, 12 on target. Fifteen with nine accurate in a frightening first half. Such numbers do not usually happen against Celtic.

In this instance, the margin of defeat could have been by so many more. Of all the concerns O'Neill, his staff and his players will carry home, this will perhaps weigh the heaviest.

It cannot be overstated how good Midtjylland were.

It will take quite something for them to be shifted from the top spot in Europe's second-tier competition, but Celtic, who had their sights set on the Champions League just a matter of months ago, shouldn't have been so easily obliterated.

O'Neill has brushed away suggestions of taking this job on a permanent basis during his two wins up until now.

Here, he was provided with a painful picture of how seismic the task at hand actually is. And it was one which might make his mind up for him.

Celtic interim manager Martin O'Neill: "It was a tough evening. There's no question about it. In terms of European football, they're a very fine side, they're strong, physically very, very strong.

"The goals that we conceded weren't good, but eventually that hadn't really much to do with physicality, or certainly two of the goals, in the sense that we'd been left 1v1.

"I think just to play football at the top level, not only do you need ability, but you need mentality and mentality sometimes overrides ability as well.

"I thought that we showed a bit of character in the second half. We could have gone under, it could have been any sort of score, but the players, pulled themselves together, pulled it round a bit and showed some character and resilience, for want of better words."

Celtic host Kilmarnock in their final Scottish Premiership game before international break on Sunday (16:00 GMT), while their next Europa League fixture is away to Feyenoord on Thursday, 27 November (17:45).