Legendary Dreadnought: Devastating Critical and Kensei Deadly Strike

[MysticRhythms]

So the Kensei enhancement Deadly Strike says that your next attack is an automatic critical threat. Devastating Critical doubles the damage on a 19 or 20 die roll for a crit. Does Deadly Strike count as a non-19/20 die roll or does it count as a 20? Does it automatically trigger Devastating Critical or does it automatically NOT trigger it?