UFC rising star Kevin Lee says Conor McGregor's newborn baby is going to RUIN his UFC career -- chewing up precious training time ... and he'll pay for it in the Octagon.
Lee is fighting Michael Chiesa on June 25th -- and says after he "beats the f**k" outta him, he's gunning for Conor's lightweight championship.
Lee says he doesn't have a wife or kid like Conor ... and while McGregor is feeding his baby mushed-up bananas, he's training his ass off to get an edge on the Irish superstar.
As for Chiesa, Lee says he only punched him at the big UFC event on Friday because he was defending himself ... and he's pissed that his designer $3,000 glasses got broken in the melee.
Lee says he'll make Chiesa pay by beating him so badly, "It's gonna change the way he views the world."