Two million tickets are expected to be sold for Saturday's must-be-won $50 million Powerball draw, Lotto says.
If it is won by a single person, it will be the largest prize in Lotto's history.
Lotto head of corporate communications Lucy Fullarton said no matter what, the jackpot would not roll over.
"Well our game rules say that if the jackpot gets to $50m it can't rollover - it has to be won that night," Fullarton said.
"So if it's not won by a single ticket - if no one single person gets all seven numbers right - then it rolls down to the next division and if it's more than one person it's shared equally between them."
It is only the third time a must-be-won draw of $50m had been reached.
Tickets were selling well, Fullarton said.
"It looks like we're on track to have about two million sold for Saturday's draw, which is a lot more than we sold on Wednesday ... 1.7 million."
The first Powerball $50m jackpot was struck in February 2020, when two winners won $25.1m each.
Another $50m must-be-won draw then took place six months later in August 2020 with the prize rolling down to Powerball Second Division.
It was shared by 10 winners, who each received $5.02m.