It was a dramatic afternoon in the velodrome after Cox – who has multiple sclerosis and suffered a calf injury in the build-up to the Games – had to be helped off the track by support staff.

The 33-year-old was not allowed to restart, as rules brought in before these Games only permit a second attempt if there is a mechnical fault with a bike.

“It was a weird one. I didn’t feel comfortable in the gate, my right side is my weak side – I just over-compensated and couldn’t balance on my weaker side, I was all over the shop,” Cox told Channel 4.

Dutch rider Caroline Groot won the first gold of the Games in a time of 35.566 seconds.

Hosts France picked up their first medal as Marie Patouillet took silver, with Canada’s Katie O’Brien winning bronze.

Reigning world champion Cox had looked strong in qualifying, recording 35.436 seconds – the second quickest overall after Groot, and ultimately faster than the time the Dutch athlete rode in the medal final.

Cox has previously been dominant in this event, having won gold at the 2016 and 2020 Paralympics – but found only heartbreak here.

She was visibly emotional and unsteady on her feet as she was helped from the track, before being embraced and comforted by GB staff.

However, BBC Sport has been told that Cox has not sustained a significant injury, whether new or to her previously problematic calf.

“I got back on the bike two weeks ago. It has been a rubbish year, this time last year I couldn’t walk as I had a relapse which effected my right side – I guess that’s MS,” she said.

“The fact I got here is amazing.”

She may be able to come back and compete for a medal later in the Games, with the mixed C1-5 team sprint taking place on Sunday.