Crotty and Williams are the two most senior midfielders in the squad, so the selectors will be hopeful they don't lose both men.
Now that Williams has been ruled out, it opens the door for the in-form Ngani Laumape to potentially have an extended run in the No 12 shirt.
If Crotty is ruled out, then it is probable Laumape will be paired with Anton Lienert-Brown at centre.
The selectors may well be eager to give the impressive Jack Goodhue his first taste of test football at centre but they would be wary about partnering him with Laumape given their collective lack of experience.
It is probable that the selectors will call in a replacement for Williams - especially with Crotty not certain to be fit either. That would likely see Matt Proctor and Rob Thompson come under consideration.
Ideally the coaches would have called up Charlie Ngatai who continues to be a hugely effective and high impact contributor for the Chiefs. But he's off to France at the end of Super Rugby and therefore not a long term prospect.
Confirmation of their midfield plans will come on Monday.