Atrocitus vs Captain atom

No prep fight takes place in a empty metropolis to the death or knock out both blood lusted no bfr

I would say Captain Atom. 

im still not sure but im leaning towards cap

Atrocitus hasn't really done anything to put him on par with Atom in my opinion. Sinestro vs Captain Atom would be a better fight.

Atom. As for fighting Sinestro, Atom could beat him too.

Atom and he stomp Sinestro too