Sean O'Malley Says UFC 248 Head-Kick Was Like Hitting Opponent W/ Baseball Bat

Sean O'Malley beat the hell outta Jose Quinonez this weekend ... dropping him with a devastating head-kick that Suga compares to being SMASHED in the dome with a solid wood bat.

TMZ Sports talked to O'Malley -- fresh off a 1st round TKO at UFC 248 -- and the 25-year-old star walked us through the combination that left Quinonez in the fetal position on the Octagon floor.

"That head-kick ... that was a powerful and heavy head-kick! It's pretty much like if I had a baseball bat. I swung as hard as I could at him. Kind of lifted him off, threw him to the back of the cage."

The finish was super impressive ... not only did Sean land the heavy head-kick, he also crushed Jose with an uppercut ... before raining down a flurry of hammer fists -- before the fight was stopped.

It was O'Malley's first fight in over 2 years ... so while the MMA world mighta been shocked at how quick he took Quinonez out, Suga wasn't.

"I knew going into any of my fights, the 1st round finish is always an option. Especially that first five minutes. I mean, I feel superhuman in there. I'm so fast, I'm so accurate. I put on some size, ya know, so I'm just more powerful," Sean says.

"So, I knew a first-round finish, I knew that could happen and honestly I kinda saw it going like that."

That's not all, as we previously reported, O'Malley told us the post-fight celly was gonna include a lot of medicine (the green kind) ... and Suga, who says he hadn't smoked in 3 weeks, had a bad case of the munchies.