It then accuses Singer of "forcibly" raping him.
Singer had been fired from a film this week after being absent from production, spurring some rumors that he was the next to be hit by sexual harassment claims.
The "X-Men" director has been sued several times for misconduct with underage boys.
Just days after Bryan Singer was sacked from Bohemian Rhapsody, the director is now facing a lawsuit for allegedly sexually assaulting a 17-year boy in Washington State back in 2003. The incident occurred in Seattle on the yacht of a wealthy tech investor who hosted parties for young gay men in the area.
The lawsuit contains details of the alleged incident, as reported by Variety, stated that Singer forced oral and anal sex on the victim, Cesar Sanchez-Guzman. Based on the complaint, Singer later approached Sanchez-Guzman and offered him career favors in return for his silence, and then threatened to assassinate his character if he did not comply. A representative for Singer told TMZ the filmmaker denies all the allegations made against him in the new lawsuit from Sanchez-Guzman.
After luring him into a cabin, Singer forced Sanchez-Gizman into oral sex, and then committed other sexual acts, according to the lawsuit.
The lawsuit was filed the same week that Singer was sacked from the Queen biopic "Bohemian Rhapsody".
The alleged victim is represented by Miami attorney Jeffrey Herman, who represented another man a 2014 lawsuit against Singer, television producer Garth Ancier and former Disney executive David Neuman.
Guzman claims he suffered "emotional distress, mental anguish, and physical and mental pain".
In 2015, Egan was sentenced to two years in federal prison in an unrelated fraud case.
The lawsuit comes just days after Singer was sacked from directing the Freddie Mercury biopic "Bohemian Rhapsody" after vanishing from set.