It was a nasty moment for the 16,000 spectators at the famous ground, but fortunately everyone involved, including the officials, kept their heads and the game was incident-free.
It was also a strong warning to the Australian and England teams that New Zealand are going to be formidable opponents as they move forward into the semifinals.
Notwithstanding Williams' scare and the usual "bumps and bruises", the tournament has been largely free of serious injuries to date. And, the top three contenders - England, Australia and the Kiwis - all look ready to show their best football from here on in.
The judiciary has been hardly bothered and the most serious injury has been Australia's Luke Lewis' tangle with a dead-ball stanchion at Old Trafford in the second round of pool games.
New Zealand look well prepared, calm and tightly focused.
Stephen Kearney has had the benefit of blending his squad together nicely and apart from Tommy Leuluai, has got all his initial selections at his disposal.
Overall, this is shaping up to be a stellar tournament for the 13-man game.
A number of the minnows have also been outstanding with just enough experience to avoid the 100-point blowouts which have characterised these tournaments in the past.