OL Reign and Canada midfielder Quinn has said they are "proud" after becoming the first openly transgender person to compete at the Olympics but added that "the fight [for transgender rights] isn't close to over."
Quinn competed at the 2016 Rio Olympics but only came out as transgender in September.
- Stream ESPN FC Daily on ESPN+ (U.S. only)
They competed in Canada's opening match against Japan, which ended in a 1-1 draw following goals from Christine Sinclair and Mana Iwabuchi.
"First openly trans Olympian to compete. I don't know how to feel. I feel proud seeing 'Quinn' up on the lineup and on my accreditation," Quinn said in a statement released through the National Women's Soccer League's social media.
"I feel sad knowing there were Olympians before me unable to live their truth because of the world. I feel optimistic for change. Change in legislature. Changes in rules, structures and mindsets.
"Mostly, I feel aware of the realities. Trans girls being banned from sports. Trans women facing discrimination and bias while trying to pursue their Olympic dreams. The fight isn't close to over... and I'll celebrate when we're all here."
Quinn is one of two openly transgender players in the NWSL. Washington Spirit's Kumi Yokoyama came out in June.
The 28-year-old said they had seen Quinn wearing a "Protect Trans Kids" sweatshirt before a game which had encouraged them to come out.
"[Quinn] wore a [sweatshirt] that said 'Protect Trans Kids' before a game, and I realised that it was what taking action looks like," Yokoyama said. "To be able to accept people you have no relationship with, that's the kind of person I would like to become and I hope we can create that society."