The Scottish government condemned gatherings of Rangers fans outside Ibrox on Saturday as Steven Gerrard's men closed to within a point of a first Scottish Premiership title in 10 years with a 3-0 win over St Mirren.
Large groups of supporters ignored coronavirus restrictions to gather outside the stadium prior to kick-off to welcome their heroes amid clouds of pyrotechnics.
Rangers could mathematically seal the title on Sunday if Celtic fail to win at Dundee United.
However, the celebrations have already begun as the Rangers squad ran off the field at the full-time whistle to celebrate with supporters outside.
Scotland remains under a national lockdown to curb the spread of Covid-19.
"We are extremely disappointed supporters have gathered at Ibrox today," a Scottish government spokesperson told Sky Sports.
"At this crucial stage of suppressing the virus, the actions of this minority of individuals jeopardises the safety of other supporters, the police on duty and the wider community.
"We will continue to engage with Police Scotland and the club."
There are fears the scenes could be repeated on Sunday if another Celtic slip-up allows Rangers to seal a first major trophy since the club went into liquidation and were forced to restart in the fourth tier of Scottish football in 2012.
"When I turned up today at the stadium, it was obviously emotional scenes," said Gerrard, who is on the verge of winning his first league title as a player or manager.
"We're still involved in a pandemic, I must mention that and it's important fans stay humble and safe. That is always the priority, fans' safety and people's safety.
"At the same time if any part of your heart can understand what these fans have been through, you can totally understand what is going on outside this stadium."
- Perfect home record -
No fans have been allowed into Ibrox all season, but that has not stopped Rangers registering a 100 percent home record, winning all 16 games and conceding just two goals in the process.
Gerrard's men now lead Celtic by 21 points. Even if the Hoops do win on Sunday, the Gers would only need a point when the two sides meet on March 21 to seal the title at Celtic Park.
St Mirren are the only side to beat the runaway league leaders in any competition this season, when they shocked Rangers in the League Cup in December.
However, there was never any doubt about the outcome this time as the hosts raced into a 2-0 lead inside 16 minutes.
Ryan Kent's twisting run and finish opened the scoring before Alfredo Morelos continued his return to form by firing in form a narrow angle.
Ianis Hagi added a third just a minute into the second half from Kent's low cross.
At the other end of the table, Kilmarnock are bottom after losing a five-goal thriller 3-2 at Ross County.
Victory takes County four points clear of Killie, who are yet to win in five games under new manager Tommy Wright.
Hamilton's 0-0 draw at Aberdeen sees them edge up to 11th.
Motherwell eased their relegation fears with a 3-1 win over Livingston to move nine points clear of the bottom two.
St Johnstone backed up their first ever League Cup win last weekend with a 1-0 victory over third-placed Hibernian.