The 20-year-old Scot again showed no deference to older and wiser rivals at the Grand Prix in Birmingham yesterday, claiming a victory in the 1500 metres that was truly first class and a further statement of her emergence as an athlete of grand potential. And with the World Indoor Championships taking place on the shores of the Baltic Sea in three weeks' time, it provided a tantalising hint that she might return home afterwards with more than mere experience for her efforts.
With one lap left, Muir pressed the ignition button and accelerated clear, her diminutive frame casting shadows behind. In the home straight, Ethiopian-born Sifan Hassan challenged, but the Glasgow University student held her ground. Her personal best time of 4:05.32 erased Susan Scott's previous Scottish record from the annals. Only Kelly Holmes among Britons has run quicker.
This emergent force appears to have no firm grasp of what potentially lies ahead. "I didn't think I was going to win," said Muir, one of the Sunday Herald's six to follow as she prepares for the Commonwealth Games. "I just wanted to stay in the top three, but I felt good with about 400 to go. I got myself in a good position and then just went for it with 200 left. You have to be like that. If you think they're better than you, they will be. I just have that mindset now where I can compete with them and I will do."
The Polish city of Sopot will be the stage for the year's only global showpiece and although domestic interest is largely shared between the Commonwealth Games and European Championships, there is a significant prize on offer before summer dawns. Having won the UK trials over 800m, Muir must now decide which distance offers the better odds before the selectors meet tomorrow to finalise the British team.
"I'll have to see how things go," she said. "I thought maybe the 800 because you get to run your own race whereas 1500m is more tactical. I hadn't run a 1500 in a while and that was fun. Both have positives and negatives."
Chris O'Hare, who opted to run the Wanamaker Mile in New York last night, will trust he will be Sopot-bound. Eilidh Child will surely get the nod, but the European silver medallist has a dilemma of her own. Third in the 400m in a season's best of 52.49, the Bath-based Scot found some satisfaction having considered a withdrawal due to her dip in form.
"I lost a month before Christmas with a calf injury, but I hadn't felt I'd lost that much," she said. "But now I know it did cost me. So now I'm going to go away and have three weeks of hard training."
It may culminate in a trip to Sopot. Or it may not.
"I'm not sure about the World Championships yet. I definitely want to do the relay, but I don't want to do the individual if I'm a second slower than last year."
The meeting was illuminated at the end by Genzebe Dibaba, who shaved five seconds off the existing world two-mile record to establish a new mark of 9:00.48. En route, she lapped both Steph Twell, who finished third on a rare indoor outing, as well as Jo Moultrie in fifth.
"To run on your own like she did for so long was just amazing," said Twell. "But the crowd noise was lifting me as well."
Holly Bleasdale maintained her unbeaten start to 2014 by winning the pole vault even though the Lancastrian could not quite recapture top spot in the rankings after coming up short at 4.77m.
In his first outing since last August, the Olympic long jump champion Greg Rutherford made an uncertain return, no-jumping on his initial attempt before ending up third, a return matched by London 2012 bronze medallist Robbie Grabarz in the high jump with his training partner David Smith in sixth.
Jamie Bowie may get a chance of redemption at the World Indoors after shoving himself into the frame for relay selection. The Inverness Harrier set a personal best of 46.58 secs in the 400m to finish third behind domestic rivals Richard Buck and Michael Bingham. Having been dropped for the 4x400 final at last year's World Championships, the Scot would cherish another shot. And with pressure to perform increased by his inclusion on the Lottery-funded list, Bowie made a vital timely point.
"I'm not going to get a place as an individual, but it was important to prove to myself that I could get the qualifying standard," he said. "That's faster than I ran at the British outdoor championships last summer so it's a sign that I'm getting better."
Guy Learmonth's world indoor hopes were ended when he came fifth in the 800m.