My instructor was very interested in the psychology behind fighting, and what was going on in the fighters minds. He told me this.
Fightings mostly about your reputation, so the fighters who have won a lot of fights have a good reputation. The person who gets into the ring next to them, that reputation is in the back of their mind.
So if you can psyche someone out youre already halfway there.
Taken in Chiang Mai, Thailand during the SOTM World Tour.