The UFC star recently spoke to TMZ Sports, and let's just say he wasn't impressed with The Problem Child's performance during his 8-round, split decision loss to Tommy Fury last Sunday in Saudi Arabia.

"It seems to me like Tommy Fury was boxing bad against his last few opponents on purpose, know what I mean? Or Jake Paul's just a terrible boxer, even more worse than I thought. I was giving him more credit than I thought he deserved," Pimblett told us.

Of course, one judge scored the fight 75-74 (4 rounds apiece, but Jake had a 10-8 round in the 8th), while the other two had it 76-73 (6 rounds to 2 for Tommy).

"Tommy won anyway and I thought it wasn't a split decision, either. I thought it was a unanimous decision. He won most rounds."

Now, the 28-year-old speaking out against Paul isn't new -- remember, the two stars went back and forth last year after Pimblett suggested his fight against Anderson Silva was fixed.

Jake even offered Paddy $1 million if the UFC fighter could beat him in a 5-round sparring session. That hasn't happened, yet ... so we asked Pimblett if he's still down to do it.

"Yeah, if he wants to," Pimblett said. "I don't give a f***. I'll spar with anyone."

In the meantime, Pimblett's getting into the fitness business, releasing a workout supplement, Paddy “The Baddy” Everything Ultimate Pre-Workout with ABE that's only sold at The Vitamin Shoppe ... and he's stoked.

"It's my lil' boost of coffee in the morning to wake me up and make me get up and actually get out and see the day," Pimblett said.