Australian professional footballer Josh Cavallo has publicly said he is gay, adding he wanted to show "everyone is welcome in the game of football".
Adelaide United midfielder Cavallo, who has represented Australia at Under-20 level, becomes the only known current male top-flight footballer to be out.
Cavallo announced the news ahead of the new A-League season in a lengthy social media post.
The 21-year-old said it was "astonishing to know there are no gay professional footballers who are out and actively playing" and that he wanted to show "others who identify as LGBTQ+ that they are welcome in the football community".
American Collin Martin, who plays for the second tier San Diego Loyal, also came out in 2018.
Cavallo has been praised by players in the Australian women's national side, with Chelsea’s Sam Kerr tweeting "Good for you" and Arsenal’s Caitlin Foord adding: "Respect, the strength to speak out and own who you are."
In his post, Cavallo said: "Being a gay closeted footballer, I’ve had to learn to mask my feelings in order to fit the mould of a professional footballer.
"Growing up being gay and playing football were just two worlds that hadn’t crossed paths before.
"In football, you only have a small window to achieve greatness, and coming out publicly may have a negative impact on a career.
"As a gay footballer, I know there are other players living in silence.
"I want to help change this, to show that everyone is welcome in the game of football, and deserves the right to be their authentic self."
Cavallo was met by an outpouring of support and affection following his announcement.
Adelaide said in a statement: "Today, Josh Cavallo speaks his truth to the world and demonstrates profound courage.
"Adelaide United, not only as a football club, but as the embodiment of an inclusive community, supports a remarkable and brave person.
"We stand alongside Josh for proudly being true to himself and will continue to love and support him as a member of our beautifully diverse family."
The A-League congratulated Cavallo and also Adelaide "for creating a safe and inclusive space", adding "football is a game for all – if you love the game, you're welcome here".
Football Australia chief executive James Johnson said: "Football Australia wishes to commend Josh’s bravery to come out as the only openly gay player in the A-League Men competition.
"His courage to be open with himself and share that part with others is inspiring and will hopefully inspire more footballers to do the same in the future."
Ex-Australia international Craig Foster said: "No one should have to hide who they are and the ball doesn’t care about colour, race, religion, gender, sexuality. Just how you play. That should be life.. all the best this season."