The Spurs might suck this season, but one fan single-handedly made Sunday's game a whole lot better ... by absolutely dominating a lip sync challenge to Kelly Clarkson's "Since U Been Gone."
It all went down at the AT&T Center in San Antonio during the Spurs' matchup against the Portland Trail Blazers ... when the jumbotron cam focused in on 27-year-old Briana Saldaña to show off her skills -- and she didn't hold back.
Check out the awesome vid -- Briana jumps from her seat and uses her drink as a makeshift microphone ... dancing and even including her man in the routine.
The crowd absolutely loved it ... and clips of Briana's performance quickly spread like wildfire on social media.
We know what you're thinking, but everyone affiliated with the viral moment swears up and down that this was NOT a staged act ... and it just so happened to come out better than anyone could have hoped.
No word on if Kelly herself got to check out the clip ... but it's only a matter of time.
Bravo, Briana -- and the Spurs better bring her back for an encore!!