Renshaw led Australia's fightback on the day one against South Africa, unbeaten on 46 and taking the tourists from 6-124 to 6-187 alongside Pat Cummins (33no).
The Queenslander was only brought back into Australia's side himself as an opener last Test in Darwin, scoring eight in the innings victory over Bangladesh.
He said he was then told on Thursday that there was a possibility he would go back to the middle order in Durban, with Nic Maddinson's shock return at the top.
Maddinson's selection will remain under scrutiny after his late call up to the squad resulted in a 33-ball duck at the top of the order.
Renshaw batted in the middle order in one-day cricket for Australia, and was at No.5 for a tough tour of India in 2023.
Prior to that, he last batted consistently there for Queensland in late 2021, before moving back to open in recent years.
"I just prepare as much as I can for whatever. With the one-dayers ... it shows I can be pretty versatile," Renshaw said.
"For me it's not too much of an issue. It's just waiting to bat. It's probably the toughest part for me and it's been a while since I've done that in red ball.
""We've seen a lot (of movement) in this team with different conditions, Heady going up to open.
"It's just being pretty versatile and pretty open with what we need to do."
Renshaw did have the added advantage of a full lunch break knowing he was about to walk out, with Marnus Labuschagne lbw on the last ball of the first session.
That allowed Renshaw to hit around 20 balls in the nets before coming out, replicating a similar process to opening.
"I was getting my eyes used to the light, get the body moving how I wanted to," the 30-year-old said.
"I think at times we can bat in the morning and then eventually you're bat at 3 o'clock and you'll be a bit behind."
Where Renshaw bats in the next Test at Gqeberha could again be up for debate, with Australia holding hope Cameron Green could return to the side.
Josh Inglis has also received positive news on his fractured finger, and is expected to fly back to South Africa before the series is out.
How soon he is cleared to play remains unknown.
Coach Andrew McDonald has also previously floated the idea of batting orders changing between innings, based on conditions.
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