"I have no doubt in my mind that I'll beat Dos Santos," said Shane Carwin before his bout against Junior Dos Santos at UFC 131. At the fight proper though Dos Santos outclassed Shane, leaving his face a crimson mask. Then after the fight Carwin remarked on his blog that he knew he faced a great obstacle in Junior Dos Santos. What happened to having no doubt?
It's classic sports psych-up talk. The operative words are in my mind. If someone truly has no doubt about something they will leave out the words in my mind. Adding those three words is like a disclaimer or exit clause, just in case things don't go according to your prophecy. Simply saying "I have no doubt I will win" is much more blunt and even arrogant. The problem is if things don't go according to plan you face ridicule and a good chastising for being so sure of yourself.
However if you include in my mind in the mix you can come out afterward and say that was just what you thought (or wanted to think) would happen. People won't blame you for being human and believing in yourself. It's less brash and cocksure when you say in my mind. It's just saying you're optimistic (or trying to be), rather than bullishly adamant.
But that's beside the point. The moment someone says "in my mind" it is already an admission that they don't have complete belief, but rather it says they are just trying to put a positive spin on things. If you had ultimate confidence you would say "I have no doubt I'm going to win" and leave it at that. In my mind is really little more than saying you hope things turn out well. Nothing wrong with that, but it's just not the ultimate statement of intent and is hardly the chilling message you want your opponent to receive. So why say it in the first place?