All Blacks centre Williams announced on Tuesday that he will fight Laundy the weekend after the All Blacks' Test against Italy.
New Zealand coach Steve Hansen has already given the green light for Williams for his next bout, saying the fight would be a low-key affair.
“I think he’s just going to get off the plane and do it. It’s the sort of athlete he is,” he said.
"We've got guys boxing all the time, as part of their training. Again, my understanding of the fight is that it's more of an exhibition fight I think than a go down and knock yourself out fight.
"You're probably better off having a good yarn to him about it, because he'll be able to fill you in on all the details. But I don't have any problem with him doing it."
The pair will fight on December 1 in a charity event called 'Banger in the Hanger' to fundraise for youth homelessness and the Auckland City Mission.
Williams has had seven fights in his fledgling boxing career and won all seven, though his opponents have often been arguably past their prime.