Oct 21 - Australia will be hoping opener Travis Head goes on to post a big score in a rearguard action against South Africa on the last day of the second test on Thursday, but it remains unclear whether the injured Steve Smith will be able to help their cause.

Australia will resume on 156-4 in their second innings, after being asked to follow on, with Head on 87, needing effectively to bat for most of the fifth day to have any chance of avoiding defeat and preserving their lead in the three-match series.

Head’s power hitting gives him the ability to take the fight to the bowlers and blunt the attack, but it is Smith’s vast experience that could be crucial to the tourists in their precarious position.

The 37-year-old former captain was top scorer for Australia in their worst first-innings batting return in a decade as they were skittled out for 99. He batted, however, in obvious discomfort with a neck injury that required on-field treatment.

Smith’s woes distracted from him reaching 11,000 test runs – the third Australian to achieve the feat after Allan Border and Ricky Ponting – before being bowled for 28 by Wiaan Mulder.

He did not come out to bat in his regular No. 4 spot in the second innings, staying in the changing room with a brace around his neck.

CHANGES ON THE CARDS FOR LAST TEST

Whether the injury impacts his ability to play on Thursday or in next week’s final test is not clear, but already Australia’s woeful batting display suggests the selectors will be re-thinking the line-up for Cape Town.

Marnus Labuschagne, Nic Maddinson and Beau Webster should all be in the spotlight when the panel sits down ahead of next Tuesday’s start.

"I'm not going to sit here and hang anyone out to dry,” coach Andrew McDonald told reporters on Wednesday when asked about possible changes, but he acknowledged his side had suffered a "significant setback".

"It was only a week ago we were a really, really good team," he added.

Labuschagne has now gone 46 test innings without scoring a century, and his second dismissal on Wednesday put his approach in the spotlight, leaving his side further in the mire.

He and Head had put on 92 for the second wicket as the home bowlers tired but instead of continuing the fightback, Labuschagne took on spinner Simon Harmer in a fierce gale and was caught skying a rash shot, precipitating the fall of two more Australia wickets before stumps.

"There's probably some shots players would like to take back," McDonald said.

"When you do that hard work, you've got to cash in, and unfortunately that wasn't the case for Marn. He’d be disappointed, we're disappointed and we find ourselves in this situation," the coach added. REUTERS