When Mitchell Marsh dropped Aiden Markram at first slip before lunch on day four, it was not only the spillage of Australia's last chance to win the Port Elizabeth Test, but also the revelation of a groin injury for the allrounder that has the potential to have ruinous consequences for the tourists.

Not only is Marsh a vital bowling option for Australia, as proven by his spells of reverse swing in South Africa's first innings at St George's Park, he has also been their best-performing batsman, soaking up more balls than any other member of the touring team and going closest of anyone to a century with his 96 in Durban.

Even if the 10-day break between the Port Elizabeth and Cape Town matches is enough to have Marsh passed fit for Newlands, it will leave him needing to be carefully managed as a bowling option, lest a worsening of the injury leads him to being ruled out altogether. Given the struggles of various other batsmen on the tour, this is a scenario Steven Smith can not afford.

"He's got a bit of a groin strain so he was struggling to move a little bit," Smith said. "I was told at the break that he can actually run, so unfortunately he could've been out on the field when he was in the slips, but still should've taken that catch but everyone drops it every now and again, I've been pretty guilty myself in recent times. It's just one of those things and we'll move on."

Marsh had entered the Test with a bout of gastro that had him well below 100% fitness on day one. David Saker, Australia's assistant coach, has said that Marsh's value to the team went beyond runs and wickets to dressing room presence and burgeoning leadership skills. "On the first day he had some gastro, he obviously wasn't feeling that good, but once you take the field, when he went out to bat, you've just got to get on with it," Saker said.

"It obviously didn't go the way he wanted, but since that time he's had some really good contributions, two really important wickets for us and a fantastic batting performance. His form since's he's got back in the Australian team has been fantastic for us, he's not just a batter, he does some bowling for us, he's a fantastic person in the dressing room for us and a future leader of the team, so there's more than just the package you see from the outside because inside he's a very valued member of our team."

While none of Mitchell Starc, Josh Hazlewood or Pat Cummins have reported injuries at the end of back-to-back Tests, by the conclusion of the second match they were all down somewhat in pace when compared to Durban, with the lack of snap being capitalised upon by AB de Villiers in particular. This also created a contrast with Kagiso Rabada, who notably beat several players for pace, not least Marsh himself in the first over of the final morning.

"I think all the quicks are going really well," Smith said. "I haven't heard today, but before today they were all feeling fine, so hopefully with a good 10-day break they can freshen up a little bit and in regards to Mitch Marsh it's a good break now between now and the next Test match and he's telling me he'll be fine but we'll wait and see how things go."