Jab to body/chest followed by right cross/hook upstairs. Never fails. Floyd/Maravilla are great at this, only of course Sergio is a southpaw uses a southpaw jab to body then straight left upstairs.
1) Jab - the punch that differentiates the boxer from martial artists and all the other kind of fighters. The jab makes boxing. 2) Hook - hard to see coming if setup well. This makes it more deadly than the cross despite having less power. Countless fighters have been caught blindsided and knocked out cold by hooks.