Plant a nanobot in her mind, have the nanobot run through Wonder Woman through illusions of combat that test that warrior's heart that got her through Karfang's poisonous corruption that we just read about. Basically, turning her biggest strength into her biggest weakness - her need to win at all costs.
The nanobot was designed from the Mad Hatter's arsenal of mind-control technology, but of course Bruce had to improve on the model, making it so good it fooled even Wonder Woman. She did not apply the lasso and deduce that her mind was being f'ed with. Her the mental illusion of a combatant had her focused on all levels, concentration, will, physical, that had the strain of the illusion gone on for much longer, Diana (of all people) would have died from exhaustion and a heart attack.
Oh, and the opponent that Diana fought in her mind? Another woman like her, with near identical fighting features and style, and the ability to take hits as good as she got. Which subtly implied that the only person who could take down and be a threat to Wonder Woman IS Wonder Woman.