AS Celtic toiled through their recent four-game run without a victory, some concession was given for their stuttering form because of the personnel issues caused by the Coronavirus pandemic.

And yet, back to full strength last night, they were humiliated on home soil by a Sparta Prague side that arrived in Glasgow minus six of their own first-team regulars. A team that had shipped seven goals in two Europa League group games to Lille and AC Milan. A side with no domestic football in their legs for four weeks, and who by all reasonable expectations should have been rustier than a tin pail in a monsoon.

Instead, it was the Czechs who were sharper in every department, scoring four times against a shambolic Celtic defence and hitting the woodwork on three occasions too as they headed home with the three points that Neil Lennon had earmarked as vital to Celtic’s chances of progression from the section.

Their hopes of doing so now look in tatters, but perhaps that is the least of their worries. They have now garnered just one win from their last six matches. If the draw in Lille last week and that sole victory over Aberdeen on Sunday were seen as steps forward, this was a massive leap back.

Lukas Julis became the first visiting player to score hat-trick at Celtic Park since Eric Black did so for Aberdeen back in 1983, and it is hard to recall Celtic putting in a worse display in the intervening period.

Leigh Griffiths very briefly made a contest of the game when he pulled Celtic back to 2-1 just after the hour, but by the time Ladislav Krejčí nodded home at the back post for Sparta in injury-time, the Celtic players were already well beaten.

This was the same Celtic team that swept aside Aberdeen in perfunctory fashion at Hampden on Sunday, with Tom Rogic keeping his place in behind Odsonne Edouard after his eye-catching display in that game. It’s only the second time all season that Lennon has had the luxury – or the notion – to field an unchanged line-up. He will certainly not be tempted to repeat the feat when Celtic visit Fir Park to take on Motherwell on Sunday.

There were frequent pyrotechnics outside the stadium early on, which at least provided a backdrop to the match of sorts, and a further bonus was that UEFA couldn’t fine Celtic for their use on this occasion.

Celtic started brightly but only had a half-chance during a stramash when Moi Elyounoussi’s shot was blocked inside the area to show for their early pressure.

Sparta turned the tide though after 20 minutes, and they never looked back. They were laying siege to the Celtic goal for a spell and hit the woodwork through the excellent David Karlsson, who had a loan spell at Kilmarnock once upon a time.

Julis had a close-range volley tipped over by Scott Bain, but from the corner, he put Sparta ahead. The delivery from the right was glanced onto the post by David Hancko, and the Celtic defence were static as Julis pounced to hammer into the roof of the net.

It was yet another set-piece goal conceded by Celtic, and in truth, it had been coming.

Celtic almost restored parity when Ryan Christie’s delightful inswinging cross found Elyounoussi creeping around the back, but the Norwegian’s deft touch grazed the top of the bar on its way over.

Jeremie Frimpong then stripped past his man on the right and cut back for Rogic, but his effort was weak and gathered by Nita, allowing the visitors to stun Lennon’s men with a lightning counter to move two ahead right on the stroke of half-time.

Nir Bitton looked to have halted Sparta’s forward momentum as he forced Karlsson wide, but he dug out a cross which Scott Brown could only nod as far as Adam Karabec. He turned the ball inside to Julis, who side-stepped Callum McGregor and curled the ball low past Bain. Had there been 60,000 fans inside Celtic Park, the silence would have been just as striking.

The Celtic manager may well have been dumbfounded too by what he had just witnessed from his men, but there is a fair chance he wouldn’t have been lost for words as they trooped into the dressing room.

Having blown a two-goal lead at the interval in their last Europa League outing in Lille, it was Celtic’s turn to claw back such a deficit, but the malaise remained at the start of the second half. Bain passed the ball straight to Julis as if encouraging him to bag his hat-trick, but luckily for the Celtic keeper the attacker ballooned over on this occasion.

Brown was the next offender, inexplicably passing the ball over the top of his own defence to play Karlsson in down the right, but Shane Duffy got back to spare his captain’s blushes.

Just before the hour Lennon eventually decided to twist, removing Brown and Elyounoussi to throw on Griffiths and Hatem Elhamed and switch to a back three.

The game was almost killed stone dead though as Sacek pinched the ball and strode forward before unleashing a low effort that bounced to safety off the inside of the post. Just as had happened to Celtic previously though, Prague were immediately punished as Celtic got back into the game.

Rogic received the ball in the area and produced a delightful touch to work the space for a shot that Nita saved, but Griffiths crashed home the rebound to breathe new life into the contest.

It would be short-lived. Celtic were caught on the counter yet again as they piled bodies forward in search of an equaliser, Elhamed giving the ball away cheaply to allow Karlsson to exploit the space left behind once more.

He charged down the left and squared for Julis to tap home from close range for his hat-trick. Game over.

When Krejčí nodded home in stoppage time from another almost comically simple goal, the Celtic players would have been grateful that the fireworks were coming from outside the ground on the night that their Europa League dreams all-but blew up in their faces.