Former Celtic boss Neil Lennon says it is crystal clear that having fans back in stadiums has been pivotal in inspiring the revival of Celtic's form this season.
Lennon, 50, cited the lack of supporters as a major problem as his team relinquished the Scottish League title and led to his resignation early in the year.
Football fans are often regarded the 12th man and their presence at match venues has had a massive impact on several results.
Match-going football supporters are an inescapable part of the round-leather game, from the racket fans make, to the money they spend on attending games and betting sites, footballers and even the Greatest English Club Managers don’t take their presence for granted.
The volume fans generate, meanwhile, can be louder than a concert.
But with mass gatherings and stadium attendance off limits due to the Pandemic, clubs such as Celtic have paid the ultimate price.
The former Celtic boss said, "I always believed the return of fans would bring the buzz back."
"Not only to the club but the players. I think that's what's evident now."
After a run of three matches without a victory last season, Celtic have won their last five games - scoring a total of 16 goals - under new manager Ange Postecoglou.
However, Lennon does not buy into the claim that the switch in the dugout is a factor in that change in fortune on the field.
Lennon tells BBC Radio Scotland, "I take exception to the theory that they weren't playing for me and now they're playing for Ange."
"Because the year before for me they were incredible - we beat Lazio and won a treble - but, when the lockdown came, it affected the players differently.
"We were in the midst of a pandemic. Players were coming into the club after being sold that Glasgow was a great city, there would be big crowds and a nice social life. They had none of that."
For the first time in over 610 days Rangers and Celtic went head-to-head in front of a packed arena. However, Celtics supporters were not allowed at Ibrox.
Celtic fans were locked out of the Ibrox derby showdown last weekend after Rangers chiefs performed a U-turn.
Reports suggest Celts were set to get about 700 tickets for the Premiership encounter – and the briefs were printed up and sent forward to Parkhead.
But Rangers pulled the plug after they could not get cast iron assurances the situation would be reversed when the teams met in the East End in January.
In that derby, Celtic suffered from absence of their fans, as Filip Helander's second-half header saw home side Rangers beat visitors Celtic 1-0 in the first Old Firm meeting of the new campaign.
Helander's 66th-minute goal was enough to make the difference between the two sides in what was a cagey, tight and tough encounter between the Glasgow teams.
Rangers and Celtics could have scored before the break, only for Celtic forward Odsonne Edouard to miss from just six yards out, before Rangers attacker Ryan Kent hit the woodwork.
But the home team - with boss Steven Gerrard not in the dugout after a recent Coronavirus outbreak at the Scottish champions - held on to move to third position on the log and open up a three-point lead over the visitors, who remain sixth.
With no Celtic fan at Ibrox, the home side tore into their visitors right from the start in what was an agitated opening, albeit without testing goalkeeper Joe Hart.
Absence of fans counted for nothing in Celtics third match of the season as they laid down a remarkable marker to league challengers by thrashing 10-man St Mirren 6-0 at Parkhead, with David Turnbull netting three goals for the home team.
Liel Abada scred the opening goal after 17 minutes, before Alan Power's red card made the visitors' task a lot harder, with Abada
soon scoring the second goal for Celtic.
Thereafter it was a matter of how many more goals for Ange Postecoglou's side, with Turnbull scoring twice more before the break, before Odsonne Edouard scored just past the hour-mark.
Turnbull finished of his hat-trick with a close-range goal with six minutes left.
A new hero was discovered upon the return of Celtic fans in the League game against Dundee United as Kyogo Furuhashi bagged a hat-trick on his home-debut in the 6-0 win.
The Japanese scored two goals from close range in the first half of the encounter before sealing his treble instantly before going off to the applause of 24,500 fans midway through the second half of the match.
After scoring on his first start for the club in the UEFA Europa League victory against Jablonec, Furuhashi endeared himself to the Celtic fans with his work-rate and skills, charging down clearances and winning back the ball from opponents.
Hundreds of fans had gathered before the match to protest against the board of the club over a perceived lack of backing for the manager, who began with four summer acquisitions.
But fans who were allowed to enter the Celtic Park had nothing to complain about as their side drew level on three points with defending Champions Rangers following the champions' surprise loss by Dundee on Saturday.
Even on their return to the Scottish Premiership, John Souttar's last-gasp winner stunned Celtic as Hearts secured a 2-1 win, showing that they really missed their fans.
For them, it's the start the new boss would have dreaded after their UEFA Champions League exit in midweek.
It quite obvious that the return of their fans to the stadium will furtherboost the morale of the team, serving as the 13th man and always spur them to victory. Who know, their return could spur the team to glory this season, at the expense of Rangers.
As regards Rangers, despite having a coach that has the quality of becoming one of the greatest English club English Club
managers, might come short this season following their Champions League outster.