Not taking credit away from Nonito because he landed it, but that cut saved him. It happened early and Inoue was protecting it for most of the fight. I think had he not been cut, he would have taken Nonito out 6-8th round.
That cut happened because of a picture perfect left hook. Yeah, it did change the momentum, I agree. Inoue looked to draw and bait the counter more afterwards. But Donaire is a wily fighter, and was there to win.
