Knowing every alien language makes cheif overrated, and a know-it-all.
The Predator is a completly new species to Cheif, as Cheif has already fought the Elites
(Which are a copy of the Predator, the mandibles and cloaking)which makes him used to them, but not the Predator, Cheif can probably take down an Unlbooded Predator(that's if it doesn't stealth attack him), but not Blooded or Fully Blooded.
So, Cheif won't know what hit him, when the Smart Disc cuts off his head(Or is just decapitated with a quick stealth attack)