Cape Town - Proteas coach Ottis Gibson insists that he has learnt a lot from his side's recent dominance against Zimbabwe, but the next step on the road to the 2019 World Cup is a three-match ODI series in Australia next month.

The squad for that series is yet to be named, but the news coming out of the Proteas camp on Sunday after the third T20I against Zimbabwe in Benoni was washed out was that Hashim Amla is still injured and will miss the Australian tour.

Amla has been suffering from a finger injury that he picked up on Caribbean Premier League duty last month and he was initially expected to recover by the Australian tour, the decision has instead been taken to give him a prolonged rest.

Now 35-years-old, Amla is expected to open the batting at next year's World Cup alongside Quinton de Kock. Together, they form one of the most respected and feared opening partnerships in ODI cricket.

De Kock, though, was also rested for the Zimbabwe ODIs which allowed Aiden Markram and Reeza Hendricks to get a chance at the top of the order.

With Amla out, one of those two is now likely to be given the chance to open alongside De Kock in the first ODI against the Aussies on November 4 in Perth.

"We know that Quinton and Hashim have been a fantastic opening pair for the Proteas for a long time, and we also know that Reeza Hendricks and Markram have also been very good in franchise cricket. We wanted to see how they go," Gibson said on Sunday, looking back on the Zimbabwe series.

"We know where we are with those two and we know that they are both very good players."

The window is closing on South Africa's wiggle room when it comes to experimentation ahead of the World Cup, and this tour of Australia is likely to be the last time that Gibson tries new combinations before he begins to settle on his squad and prepare for the global showpiece.

"There are a lot of guys that will be in our thoughts when choosing that squad to Australia. Hashim is injured and out of that tour ... we've discussed that with him already," Gibson said.

"We're going to give him as much time as we can to get him ready for the next cricket that he has coming up, so he's not going to be considered.

"For the past 12 months we've been looking at players and in the next couple of months the window is closing.

"We're getting closer and closer to the guys that we want on the journey. In the next couple of series - Pakistan and Sri Lanka - we really want to be focusing on 17 or 18 players that we will be looking at."

In the end, Gibson and the brains trust must settle on 15 names to make up their World Cup squad.

The tournament starts on May 30.