For Major League Soccer's Robbie Rogers, breaking another barrier for gay athletes by becoming the first openly gay male to compete in a major US professional team sport marked the latest step in his long journey.

The Los Angeles Galaxy midfielder was greeted by cheers from a crowd of nearly 25,000 in Carson, California, when he entered Sunday's game as a substitute in the 77th minute with his team leading the visiting Seattle Sounders, 4-0.

"Earlier today I was really nervous," Rogers said after the hallmark moment, which came a day after he was introduced as the Galaxy's newest member. "OK, this is a soccer game. I've done this a million times. But then obviously I know, I'm not naive, I know people are watching.