The double World Cup-winning captain was initially thought to be out for at least six weeks following a calf strain in the Boks Rugby Championship opener against Australia at Ellis Park in August.
Kolisi ran out at eighthman due to the lengthy injury list and the suspension for the incumbent Jasper Wiese, who will be available next week.
Speaking to the press on Monday, Erasmus revealed that the prognosis is much improved but he won't rush to play his captain unless he is 100% match fit.
"We brought 36 guys on tour, Jasper is only available next week, and Siya is touch-and-go for this week," said Erasmus.
"It's again one of those calls that must be made with a little bit of a longer-term mindset. He'll definitely be available next week.
"We will only announce the team on Thursday, but at this stage, he is bracketed just to make 100% sure we don't push him.
"Initially, we thought he was going to be out with a six to eight-week injury, and then the scan came back much clearer. So, we'll make that call a little bit later in the week, but next week, he will be 100%.
"It's a long season, and we still hope that Siya can play another year or two for us and bringing him back one game too early might just bugger it up six or seven weeks and the rest of the year.
"It is an emotional decision, and it's one that we haven't quite finalised. The heart says let's play him, but the mind says let's watch until Thursday."
In terms of team selection, Erasmus indicated there's unlikely to be any surprises when he announces the team later this week.
"Normally, we don't experiment too much against New Zealand," he added.
"We try to put the fittest, in-form, available team out there, and I think this will be the case. The most in-form, fittest available team will be picked because it's a must-win for them and for us now; it's not like we have the luxury of saying we beat them twice.
"Last year, we beat them twice, and we could experiment against Argentina. Had we lost last year against New Zealand or Australia, you know, we couldn't have experimented like we did with Argentina away. So, no, it will pretty much be everybody who's fit and healthy will be on board."
As the Springboks prepare to face the All Blacks at Eden Park, head coach Rassie Erasmus is embracing the challenge of taking on a side that has made the Auckland venue such an impenetrable fortress.
The All Blacks are without the services of six players as they prepare for a blockbuster clash against the Springboks at Eden Park this Saturday.
As he closes in on a little piece of history, Australia front-rower James Slipper is taking a game-by-game approach to his career.
Springbok assistant coach Jerry Flannery is aware that the World Champions have to be at their best if they are to defeat the All Blacks at Eden Park on Saturday.
