The victory came after half of the tight group went wrong in the final stretch of the men's 48-kilometre roller ski race in Trollhättan.
"I don't know what happened and I don't know if I did the right thing or the wrong thing. It was a bit chaotic, that's what happens," Myhlback told TV4 about the incident.
Tobias Mattson, competition director for Alliansloppet, says the jury will meet to investigate the foul.
Something has gone wrong and we need to think about why it went wrong, he says.
On the women's side, it was a Norwegian clean sweep at the top of the results list.
Astrid Øyre Slind won in 2.03.26. This year's Vasaloppet winner Emilie Fleten came second, just over a minute behind Slind. Compatriot Magni Smedås was third.
The best Swede was Moa Hansson in sixth place, ahead of Alvar's younger sister Vera Myhlback in seventh place.
