The loss of George North is the latest injury blow to hit Wales' autumn series, with the likes of Adam Jones, Dan Lydiate, Alun Wyn Jones, Josh Turnbull, Richard Hibbard, Dan Biggar and Ian Evans all unavailable.
The 20-year-old suffered a hip injury in training on Tuesday which has ruled him out of the clash with the world champions, although he could yet be fit to face Australia a week on Saturday.
North has scored 11 tries in his 25 Tests for Wales, and was seen as a key attacking threat for the Six Nations champions as they look to get back on track after starting their autumn campaign with demoralising defeats to Argentina and Samoa.
But 21-year-old Williams, who won his one and only Wales cap to date against the Barbarians in June, has excelled for the Scarlets so far this season, albeit in his preferred position of full-back.
McBryde said: "It is a blow, we are well aware of the threat George poses with regards to his strong running, ability under the high ball, breaking tackles and his work-rate.
"There is no denying it is a blow, but we are fortunate to have someone like Liam, who has performed consistently well for the Scarlets, to fill in for him.
"The signs are that he can deal with it (the pressure of facing the All Blacks), but there is only one way to find out.
"You can prepare as much as you want, but it is not just a question for young players but for any senior international who has not faced the All Blacks, you don't know how you will react until you get in there.
"But Liam is quite grounded as an individual, he is well aware of the challenge ahead of him.
"One thing that is evident whenever he puts on the shirt for the Scarlets or for Wales is he is full of life, does not take a backward step and gives as good as he gets."
Wales have not beaten the All Blacks since 1953, and have suffered 24 consecutive defeats since that day.
New Zealand, meanwhile, are unbeaten in their last 19 Tests and have racked up 93 points in beating Scotland and Italy so far on this tour.
And McBryde acknowledges it will take a monumental effort if Wales are to claim an upset victory in Cardiff.
He said: "They are the one side you measure yourself against, they are the world champions, the ones you want to beat.
"They get a little bit more focus in preparation because you know what is coming.
"We have paid due respect to them, they have played great rugby and it is a great challenge. We have not only focused on New Zealand this autumn, but you know it takes something extra, something special, to match the All Blacks and to beat them.
"We have jumped on any sign of a perceived weakness.
"They have said they were not happy with their performances in Scotland and Italy. Scotland put them under a bit of pressure and managed to keep them under pressure in their 22 leading up to one of their tries, and Italy also caught them on one or two scrums and took the game to them as well."
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