User blog comment:Royice/Theory on how Zeref know Natsu/@comment-7418318-20140109194359

The victory in F-Rogue + Motherglare vs. Natsu + Atlas Flame was mostly the Dragon's doing. Even powered up by the Dragon flames Natsu still couldn't defeat F-Rogue until Atlas Flame tossed him. And it was Atlas Flame who knocked Motherglare into the Eclipse Gate.

So why would Atlas Flame assume that the boy who couldn't even defeat F-Rogue or any of the Dragons by himself would be able to best an enemy that even the Fire Dragon King himself couldn't overcome?