Chauncey Billups was introduced as the next head coach of the Portland Trail Blazers on Tuesday ... but before he talked hoops, the ex-NBA star opened up on his sexual assault allegations from more than 20 years ago.
Back in 1997, Billups -- a player for the Boston Celtics at the time -- was accused of sexually assaulting a woman at teammate Antoine Walker’s home.
The woman claimed she blacked out during the attack ... and woke up with injuries to her cervix, rectum and throat.
Billups was NOT charged with a crime .