User blog comment:Ghmorello/Chapter 895: No Step On Snakeman!/@comment-143.52.35.70-20180216120943/@comment-4374114-20180216200212

Another point in which it is suggested Luffy is using Observation Haki, unless it is just a poor translation, is the mention that he is hungry after getting slammed by Katakuri. When he then jumps up to attack again he says that he has cleared his head again. Each of these poitn to the training by Rayleigh, Luffy was distracted then with being hungry but then learned he needs to clear his mind to expand his Observation haki. Luffy has best been able to see as Katakuri does when he is doing so instinctively, as shown when Flampe tried shooting him.