Nicola Sturgeon insisted she was right to keep strict rules on pubs and restaurants in Edinburgh after fears infections are rising fast.
She admitted the decision not to ease restrictions was unpopular but warned: "It would be like pouring petrol on smouldering embers."
Sturgeon defended the decisions as public health officials and politicians prepare to set Scotland's 32 council area tiers for another week.
The First Minister will announce what levels are being imposed during a statement at Holyrood on Tuesday afternoon.
Last week's review saw Glasgow and 10 neighbouring councils leave the highest level 4 curbs. It meant shops and hospitality could reopen more at a crucial time before Christmas.
There were hopes Edinburgh's lower rate of infection would see the city move to level 2, which allows pubs and restaurants to open longer and serve alcohol.
At her daily briefing today, Sturgeon said: "The decisions in Edinburgh are tough and unpopular. I don't shy away from that.
"But if I look at the data since last Tuesday, then I have to conclude the decision we took last Tuesday not to take Edinburgh down a level was actually the right one."
In the past seven days, cases in the capital increased by 33%. Test positivity is almost at 5%, she warned.
Sturgeon said: "The judgement I and the cabinet made - and I think it is the right judgement - that when you're starting to see that kind of increase it would not be a sensible thing to do to ease restrictions. It would be like pouring petrol on smouldering embers."
Sturgeon said cases are also on the rise in Midlothian, at level 3, and in East Lothian, which is at level 2.
Aberdeenshire and Aberdeen city are also causing concern among public health officials.
"These are not straightforward decisions," she said.
"It would be much easier if it was a simple algorithm but it's not. We have to apply lots of judgement as right as possible to stop the situation deteriorating."
Sturgeon would not confirm what level Edinburgh or any other part of Scotland will go to in the review tomorrow.
"We were right last week not to ease restrictions in Edinburgh. But if there was any doubt about that, it has been dispelled in what happened to case numbers since then.
"It would simply be a risk that I don't think would be right to take on a rising trend of cases in the capital city to substantially ease restrictions."
Sturgeon would not say if her concerns meant a decision about Edinburgh had been taken for the week ahead.
She will meet her top team of government ministers on Tuesday morning and look at the latest public health advice. The decisions will be announced to parliament.
