CAPE TOWN, Oct 28 - Any doubts about Australia's top order in the absence of Steve Smith were eased on Wednesday as the visitors laid the platform for what could be a big first-innings lead in the series-deciding third test against South Africa at Newlands.

Australia finished the day one run ahead of the hosts' first-innings total of 329 with six wickets in hand, leaving the visitors well placed to clinch the series after the teams shared the opening two tests.

Opener Matt Renshaw continued his fine form with 74, while there were also unbeaten half-centuries for Josh Inglis (85 not out) and Alex Carey (51 not out), and a bright 65 from Cameron Green.

Renshaw had already been earmarked to move up from number five to open the batting before Smith withdrew from the test just ahead of the toss with a neck injury.

“We all know our jobs,” Renshaw told reporters. “Steve is obviously a massive loss for that batting group but the guys coming in are quality players.

"Cam has got a really good record and Josh has already got a test hundred. Hopefully he gets another one.

"There were no discussions about extra responsibility. It was more about how we could stick to our tempo, stick to our plans and try to build partnerships."

Smith’s replacement Inglis was particularly impressive, even after South Africa took the new ball late in the day.

"He's a very talented player,” Renshaw said. “We've seen that across a lot of the white-ball formats, but to come in today when we were under a little bit of pressure, having lost two quick wickets, and play the way he did was really positive.

"It was a very Josh innings, and I think it was really what we needed at that time."

The one batsman to miss out was Marnus Labuschagne, whose lean time in tests continued with a duck.

"Marnus is a great mate of mine,” Renshaw said. “As batters, we can get out at any point and unfortunately today was a short one for him.

"But from what I've seen in the first two tests, he's been moving probably as well as I've seen him bat.

"Unfortunately, sometimes you need a bit of luck and that's cricket. But the way he's going, I think he's very close.” REUTERS