UFC star Glover Teixeira has tested positive for COVID-19 ... and now, his main event fight with Thiago Santos is officially postponed.
Glover and Thiago were supposed to throw down at UFC Fight Night on Sept. 12 -- but Glover's COVID test came back positive on Wednesday, screwing up those plans.
The good news ... Glover's camp says the 40-year-old Brazilian legend is feeling 100%.
UFC is now gunning to re-book the fight for Oct. 3rd -- but it would no longer be a 5-round main event, according to ESPN.
Glover and Thiago are two of the best light heavyweights in the world.