The series, which also includes world champion Australia and England, will take in six stops across Australia and New Zealand.
The teams will remain in Auckland at the end for the Fast5 tournament.
The busy end to the season and tight scheduling means the star defender's workload needed to be managed during the series.
Williams said she had come to accept that if she wanted to prolong her career and avoid any further lay-offs she would have to be rested for some matches.
"It's likely that I'll have a bit of time out because otherwise I've gone from one extreme to the other, and that's not ideal." Williams, who has not played for the Ferns since last year's world championships, had her return to international netball delayed after one of her troublesome knees flared up before last month's Constellation Cup series.
But this time she claimed she was ready to go.
"I've come through all the sessions and ... I was running with no pain at all. I feel like a 17-year-old again. It's great," Williams said yesterday.
While she insisted her side was not taking South Africa lightly, Williams said tomorrow's match-up was a good opportunity to ease back in to action before the Ferns took on the more competitive English and Australian sides later in the week.
"Personally, for me, it's a good first game to come up against to try and get myself up to speed," she said.
"In training I was getting frustrated because I could see the ball, I could see what I wanted to do, but just getting the timing and co-ordination back takes time."
With the return of Williams, the Silver Ferns have made a couple of changes to their line-up from last month's historic Constellation Cup win, coach Waimarama Taumaunu keeping her promise to rotate her squad throughout the international season.
Canterbury's Anna Thompson will get her opportunity to push for a fulltime spot, replacing Jodi Brown in the shooting end, while in the midcourt uncapped youngster Shannon Francois joins the team as a late replacement for the injured Grace Rasmussen.
Rasmussen, who has a stress fracture in her ankle, was originally called in to the line-up in place of Camilla Lees, who ruled herself out of the tour because of study commitments.
Without Lees or Rasmussen, the pressure goes on Ferns newcomer Bailey Mes to step up and take on a starting role.
Mes was a shock selection in the New Zealand line-up, having played just one quarter of ANZ Championship netball this year.
After such an unexpected rise, Mes' debut has been keenly anticipated. Her opportunity is expected to come tomorrow against South Africa, and if she struggles, there is little in the way of a safety net for her.
