Rhino's horn will flail around violently and pierce the lion so badly, dead animal rights activists will turn in their graves. The rhino's armor is too thick for the lion to do much with, and the damn thing is a moving tank. It might get a few scratches and a bite on its neck, but nothing more.
I'd go out on a limb to say the rhino could knock out two lions at the same time.
The limb the rhino just crushed!
Nice play there.