Something was clearly amiss.
Her fellow competitors were all in position on their mats, shooting at the targets.
Twenty seconds later, there was a sigh of relief after what seemed like an eternity in the Norwegian camp when she finally took her position.
But what had happened to the experienced Roeiseland who currently leads the women’s World Cup standings?
“When I went to the start, our physiotherapist Ragnar came up to me and said that someone had said that I had lost something on my weapon. I checked it, and I had two magazines and six extra shots, and everything was as it should be, from what I saw,” she told Norwegian TV NRK.
The crucial recovery ahead of the shoot
It turned out Roeiseland was missing the iris aperture: a small but crucial part of her rifle - so small that she did not even realise she had lost it!
The small gadget is a viewing slot on a rifle placed close in front of the athlete’s aiming eye and is vital for accurate shooting.
“I have never experienced it before,” continued Roiseland who also had a broken ski pole.
Slovenian’s keen-eyed biathlete Polona Klemencic noticed Roeiseland's rifle was missing the iris.
She immediately notified her team’s physiotherapist Ula Hafner.
Hafner alerted the Norwegians, who did not immediately notice that their athlete had dropped the crucial gizmo.
The Slovenian physiotherapist told NRK that shortly after the start she found Roeiseland's iris aperture in the snow and made sure that the Norwegian camp was promptly alerted.
“When I gave her the pole, I also had to give her the message about the iris aperture. I could see that Marte was thinking: "What is this for?", Harri Luchsinger, the development manager of the Norwegian biathlon federation explained to TV2 Norway.
Roeiseland: Slovenia's physio is the "real hero of the day"
The Norwegian team placed the iris on Roeiseland’s stand and she had to mount it on the rifle before she could shoot.
She added, "It was never screwed in, and I just screwed and screwed and screwed. It never ended!
"But now I have experienced it, and it was a good confirmation that as long as you manage to have the focus in the right place, it will go well. Stress is our worst enemy.”
“What a day and what a team!” she posted on her Instagram page.
“A big dream came true today, Olympic champions🥇
Hafner said, “I'm glad I found it, and happy to help. When Johannes Thingnes Bø crossed the finish line, I was happy for them. I know that without an iris aperture, Norway would have had a very difficult time today."
“A big thanks to Slovenia’s physiotherapist who saved the day by finding my “Iris”, an important part of my weapon I had lost. The real hero of the day. 🦸♂️”- Marte Olsbu Roeiseland.