Tillman had tipped the scales at 128.4kg and cut a very imposing figure while Williams, set to compete in his fifth bout, weighed in at 107.9kg.
After the pair weighed in, they posed for photographers.
The men could be seen whispering in each other's faces before Williams shoved Tillman and tried to throw a right hand.
Tillman responded in kind before the fighters' management and trainers jumped in to separate them.
The press conference had been a visibly more tense affair than Williams' other appearances, with Tillman scoffing and shaking his head when the All Blacks said he would bring the fight to him.
Tillman told reporters he went to the TAB this morning and placed a $1000 bet on himself to knock Williams out.
