Kim Zolciak's Daughter Caught a Pitcher!!

Kim Zolciak's daughter is following in Mom's footsteps, and we don't mean she got a wig ... instead she's snagged a pro baller.

Sources close to the "Don't Be Tardy" star tell TMZ ... Brielle Biermann is dating Michael Kopech, a 20-year-old pitcher in the Boston Red Sox minor league system.

We're told she and Michael started chatting in March, but things started getting serious recently, meaning they're monogamous now ... a big step for 19-year-old Brielle. It's a long distance thing at this point -- she travels to Salem, VA to see his games, and he comes to Atlanta when he can.

Michael's a tall drink at 6'3'' and 205 pounds, and we're told the family loves the fact he's a gentleman. Which is good for him, since NFL-playing papa Kroy Biermann is also 6'3" ... but 260 lbs.

Dad strength is real, y'all.