Rough day at the office for ex-UFC star Sage Northcutt -- who just got his face obliterated 30 seconds into his ONE Championship debut.
The 23-year-old was taking on Brazilian fighter Cosmo Alexandre in Singapore ... when just 25 seconds into the fight, things went bad for Sage.
Cosmo cracked the kid with a solid right -- immediately turning off Sage's lights and sending him crashing to the floor face first.
JUST. LIKE. THAT! Cosmo Alexandre knocks out Sage Northcutt 29 seconds into the first round 👊 @CosmoAlexandre #WeAreONE #EnterTheDragon #Singapore #MartialArts pic.twitter.com/Nh32Z1LNjU
The ref stopped the fight and the announcer said Sage was out cold.
Don't worry, he got up and appears to be okay.
Disappointing debut for Sage to say the least ... he left the UFC after his contract was up last year and was hoping to become a massive superstar with ONE.
In fact, Sage previously told us he was hoping to parlay his MMA success into a movie career -- but it's always harder to do that following a crushing loss.
Back to the gym ...