Williams was helped off two minutes into the second half, and was led to the team bench where his left boot was taken off and ice applied.
Japan had scored first at the Deodoro Stadium, Truya Goto squeezing past Rieko Ioane’s tackle to dot down in the corner.
Their lead was short-lived, however, as Gillies Kaka exchanged passses with Akira Ioane before putting in skipper Scott Curry.
Akira Ioana crossed for New Zealand’s second but Kameli Soejima scrambled over to draw the scores level, Katsuyuki Sakai’s conversion pulling the Japanese two points clear for a famous win. (AFP)