A police helicopter circled above Celtic Park as riot vans lined up outside the stadium, surrounding the cars of players while officers struggled to hold back angry fans.

It was like a scene from yesteryear, certainly nothing that should have been happening while heavy social restrictions were in place during a pandemic. And certainly nothing that has been witnessed for some time at a soccer club that has won trophy after trophy in the Scottish game in one of the most successful periods in its history.

Before long, some Celtic fans would be kicking down barriers and clashing with police officers — two of whom were injured — while others lobbed what police called projectiles at the team’s shell-shocked players.

It was Sunday evening and Celtic had just been upset in a 2-0 loss to Ross County in the Scottish League Cup, ending a 35-match winning run in domestic cup competitions and marking the first time since 1958 that the team has been defeated in four straight home games.

Neil Lennon, Celtic’s increasingly embattled coach, couldn’t fail to hear the commotion as he walked into his post-match media conference. Foul-mouthed chants toward Lennon were clearly audible.

“It’s not been great,” Lennon said, “but there’s plenty of time to turn it around.”

Lennon, though, will do well to get through this crisis.

Eliminated from Europa League contention after just four of six group games, 11 points behind great Glasgow rival Rangers in the Scottish Premiership — albeit with two games in hand — and now out of a domestic cup for the first time since 2016, these are bad times for a club of Celtic’s stature and recent dominance.

Celtic’s players headed to Italy on Wednesday for a Europa League match against AC Milan looking for just a third win in their last 11 games in all competitions. The woeful streak of results began on Oct. 17 with a 2-0 home loss to Rangers in the league in what is always the biggest match in Scottish soccer.

Even more so this season as Celtic chases an unprecedented 10th straight league title, which would close the gap to Rangers in terms of overall championship triumphs to two. It is currently 54-51 in Rangers’ favor.

Lennon was given a vote of confidence Tuesday by the club’s chief executive, Peter Lawwell, who said the manager and playing squad “have never been more determined to succeed.”

“Having enjoyed such sustained, unprecedented success,” Lawwell said, “we now need strength in adversity.”

And now that Celtic cannot advance in Europe — having also been eliminated by Hungarian team Ferencvaros in the second round of Champions League qualifying in August — the likelihood is that domestic results will improve with Lennon’s team focusing on the league.

There’s also the opportunity to claim a fourth straight domestic treble — the league, Scottish Cup and Scottish League Cup — should Celtic beat Hearts in the Dec. 20 final of the Scottish Cup, a title match that was unable to be played at the end of last season because of the coronavirus outbreak.

Still, Celtic’s regression is undeniable amid Lennon’s second spell in charge of the club, with the biggest concern among its fans being the rise across the city of Rangers under former Liverpool captain Steven Gerrard.

The way Rangers outplayed Celtic on October was a real eye-opener, showing that the blue half of Glasgow would be a sustained title challenger this season after nearly a decade in the shadow of its rival because of financial problems that forced the team to start from the bottom of Scotland’s soccer pyramid in 2012.

While Gerrard is proving to be a breath of fresh air for the Scottish game, Lennon appears to be going through the motions having done so well to bring stability to Celtic after returning as manager following the abrupt departure in February 2019 of Brendan Rodgers to Leicester in England.

Lennon led Celtic to the title that year — it was a foregone conclusion — and again this year when the 2019-20 season was ended prematurely amid the pandemic with Celtic well clear of Rangers before final placings were determined on a points-per-game basis.

And while Celtic began this season in familiar fashion by winning 11 of its first 13 games — the only loss in that period being against Ferencvaros — the team has hit a wall since the loss to Rangers. Among the losses in the recent abysmal run were back-to-back 4-1s at the hands of Sparta Prague in the Europa League.

Sold players like defender Kieran Tierney (to Arsenal in 2019) and striker Moussa Dembele (to Lyon in 2018) haven't been replaced by ones of the same quality. One of the more high-profile arrivals in the most-recent offseason was center back Shane Duffy, who hasn’t started a match for Celtic in the past month after some costly errors.

Celtic hasn't played in the Champions League's group stage since 2017, a symbol of its decline.

Rangers, meanwhile, is taking advantage of its rival's slump, even outdoing Celtic by rising atop its Europa League group that contains Benfica. Stopping Celtic achieving “The 10” — as it is often referred to Scotland — is the biggest task this season, though.

Lennon won't give that up without a fight.

“I understand the frustrations of the supporters,” he said Wednesday. “We aren't in a great run at the minute. We are in agreement, we must do better.”

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