User blog comment:FairyRaven/Fairy Tail Chapter 337: The Golden Plains, Review and Commentary/@comment-7418318-20130628125358/@comment-7418318-20130628142420

With Natsu flying along parallel to Motherglare's back (if that makes any sense) and then smacking straight into F-Rogue I don't see how his hit could have any impact on the Dragon, beyond a bit of fire-splash, which would have lacked the necessary force to affect Motherglare, not to mention that such splash damage would have knocked it in a different direction than F-Rogue.

So it must have been Atlas alone who knocked Motherglare into the Gate, while Natsu knocked F-Rogue in the same direction.