Khan: I have the speed to beat Mayweather

The Oxford Dictionary definition of delusion

a false belief or opinion about yourself or your situation
the delusions of the mentally ill

Don't go getting delusions of grandeur (= a belief that you are more important than you actually are).

He was suffering from paranoid delusions and hallucinations.
Love can be nothing but a delusion.

2 [uncountable]
the act of believing or making yourself believe something that is not true

KHAN CHANCES OF EVER BETTER MAYWEATHER