After storming to victory at the Sainsbury's Glasgow International Match in January - setting a Scottish indoor 800m record into the bargain - she proved that was no fluke a fortnight later by winning over the same distance at the British Athletics Indoor Championships in Sheffield.
On that occasion, Muir impressively demolished a field that included former world medallist Jenny Meadows to claim her place in the GB & NI team for the World Indoor Championships in Sopot, Poland, on Friday.
The 20-year-old Glasgow University veterinary student followed that up with a blistering run over 1500m at the British Athletics Indoor Grand Prix in Birmingham last month, finishing in a PB of 4:05.32 to place her second on the UK all-time list behind double Olympic champ-ion Dame Kelly Holmes.
With reigning European champ-ion Lynsey Sharp yet to return to competitive action, Muir will head to the World Indoor Championships as undisputed British No 1 over 800m - a position further buoyed by her topping the IAAF's world rankings in recent weeks. She currently sits third overall behind Americans Ajee Wilson and Chanelle Price.
Back in Glasgow to briefly catch her breath, Muir is modest about her achievements. "It's all been going well," she says, having perfected the art of understatement.
By her own admission, the significance of her remarkable run of results is yet to sink in. "I look back at Glasgow and think: 'How on earth did I run that quick?'. Then, when I went out and ran well again [in Birmingham], even an hour later I thought: 'How did I do that?'
"It's scary to be ranked so high up in the world and faster than all these people I remember watching and thinking are really good. It feels surreal, but I'm loving it all."
Muir was the standout choice for performance of the day in both Glasgow and Birmingham, and was rewarded with two £1000 cheques. While most students would be straight down the pub, she has earmarked the money for more practical purposes.
"Although you would think running doesn't have that many costs, when you are going through a pair of trainers every few months and travelling to competitions it does add up," she says. "It's great to have that extra financial support and really humbling to know that people are recognising your performances.
"Watching the BBC coverage back afterwards and hearing Paula [Radcliffe], Colin [Jackson] and Denise [Lewis] talking about me was so nice because they are such inspirational athletes."
Birmingham was special for other reasons too, as she won on her father's birthday. "My dad was pretty chuffed," she says. "'Best birthday ever', I think he said. My parents had planned to go down to Birmingham but decided to save up for Poland instead. They were watching on television at home, so I thought: 'I'd better win or else I won't get on camera to say happy birthday'."
A few years ago, says Muir, she would have been giddy with delight to have her name merely mentioned in the same breath as Holmes, but now she's snapping at the Olympian's heels on the UK all-time list.
"I remember her being at the launch for the Glasgow 2018 Youth Olympic Games bid at Kelvingrove Art Gallery and Museum," says Muir. "I was too shy to go up and say hello or ask for a photograph, so to think I could now almost beat her time feels quite scary. It's exciting to think what can come."
But Muir, who hails from Milnathort in Kinross-shire, is reticent to take all of the plaudits, paying tribute to her coach Andy Young who she began working with in 2011. It was Young, a former World Schools 800m champion, who first spotted her talents and has helped Muir transform her former "hobby" into world-class performances.
"I have to give Andy a lot of credit because I don't think I realised what potential I had before," she says. "I think having someone believe in you makes you work so much harder to reach your goals. He plays a big role in giving me that confidence. I feel I want to run well for him as much as myself."
Her main goal in Sopot will be to reach the 800m final and then take it from there. "To go through I think you will probably have to win your heat," she says. "That will be tough. With having one of the top times it means I will be in with some pretty quick girls. Getting through my heat will be a challenge in itself, but I want to progress to the final where anything could happen. I could be first or sixth - it will all depend on how the race is run and I'm feeling on the day - but preferably I'd finish closer to the top."
Afterwards Muir, who was among the first 27 athletes to be selected for Team Scotland last September, will head to California for a month of warm weather training. "I have no races for quite a while," she says. "I will be back in Glasgow for my exams at the start of May, then I think we plan to open the racing season up quite late, probably mid to late June.
"Because I have the qual-ifying standards, we can focus on getting in a good two to three months of training after the worlds. It's exciting to be going to America because I've never been out of Europe before."