Minnesota United midfielder Collin Martin revealed Friday that he is gay, the Major League Soccer standout becoming the only openly gay male athlete on a major American sports team.

Martin, a 23-year-old American, made the announcement in a Twitter posting and statement, making the move ahead of United's Gay Pride night promotion at a home match against Dallas.

"Tonight my team, @MNUFC, is having their Pride night. It's an important night for me - I'll be announcing that I am an openly gay player in Major League Soccer," Martin tweeted.

Other US athletes have revealed they are gay during their playing careers, including the NBA's Jason Collins, American football player Michael Sam and Robbie Rogers of the MLS Los Angeles Galaxy.

Rogers become the first openly gay man to play in a top-level US sports league when he played for the Galaxy in a 2013 match. He had been the only openly gay man on a US sports club until retiring last November.

Martin, who made his MLS debut nine weeks after Rogers made his groundbreaking start for the Galaxy, is in his sixth MLS campaign after four years with DC United and two with Minnesota.

"I have been out as a gay man for many years to my family and friends and this includes my teammates," Martin said in his statement.

"I'm proud that my entire team and the management of Minnesota United know that I am gay. I have received only kindness and acceptance from everyone in MLS and that has made the decision to come out publicly that much easier.

"I want to thank my teammates for their unconditional support for who I am. In light of my experience as a professional athlete, I want to take this moment to encourage others who play sports professionally or otherwise to have confidence that sport will welcome them wholeheartedly."

MLS commissioner Don Garber backed Martin's move, saying in a statement, "We admire Collin's courage and are proud of him and of the support from the soccer community."