UFC's Brendan Allen Says Reinier de Ridder Quit During Fight, '100%'

Brendan Allen isn't mincing his words after pulling off a short-notice upset win against Reinier de Ridder ... telling TMZ Sports his opponent's team wasn't responsible for calling it quits, but the fighter himself!!

We chopped it up with Allen following his massive performance at UFC Vancouver over the weekend ... which ended when RDR failed to answer the bell to start the fifth round.

Allen said he watched back the moment RDR's corner threw in the towel ... and while Reinier's coaches swore it was their call, he had a different view.

"It was something to the fact, 'Are you okay, are you okay to keep going,' or something like that," he said. "And he said, 'No.' They said, 'Are you done?' He said, 'Yes.'"

"It had nothing to do with his coaches. It had nothing to do with his corner. He quit. They asked him the two questions. He said 'Yes' and 'No.' Again, it was in a different language. I just watched and heard the translation for what it was."

Either way, Allen got the W, leaving the fifth-ranked UFC middleweight with plenty of options for his next fight. So, who does he want next??

As much as he would love a shot against Khamzat Chimaev for the middleweight title ... he knows he has to be realistic.

"For me, the best-case scenario would probably be Dricus [Du Plessis] in April, I would assume," Allen said. "March, April, May, somewhere around there, that's the best-case scenario. But if not, you know, there's still Sean Strickland and I guess [Israel Adesanya]."