National selector Mark Waugh has confirmed Australia will err on the side of caution regrading Mitchell Starc's fitness, with the pace spearhead an unlikely starter for the Boxing Day Test because of a foot injury.

Starc has been cleared of serious damage but remains in doubt for the fourth Ashes Test at the MCG because of a bruised heel.

The left-armer, who remains on crutches because of the injury he sustained during Australia's innings victory in the third Test at the WACA, will land in Melbourne on Friday.

The painful injury requires rest and Starc has limited time to prove his fitness before Australia starts its push for a 4-0 lead in the series against England on Tuesday.

Selectors will be understandably keen to ensure Starc is fit for a four-Test tour of South Africa that follows the Ashes.

"Common sense prevails," Waugh said on Fox Sports.

"You ask the bowler how he's feeling and the medical staff will assess it as well.

"If it was 2-1 down or 2-1 up and this was a Test match we had to win, you might push the envelope a bit further than when you're 3-0 up.

"Common sense says, if he's not quite right I think they'll err on the side of caution. That would be common sense to me."

Australia is yet to declare Starc a non-starter, wanting to give the express paceman every chance to show his landing foot is up the rigours of five days of Test cricket.

If he is ruled out, Jackson Bird will take his place in Australia's XI.

Aussies warned not to risk Starc

Former Australia captain Allan Border suggested it would be sensible for Starc to miss the fourth Test.

"He's had different problems with that same foot," Border said.

"Having secured the Ashes, probably no real need to risk Mitchell in Melbourne. Hopefully he gets himself right for the Sydney Test."

Mitchell Starc has played a key role in Australia's Ashes series triumph. ( AAP: Dean Lewins, File )

Starc noted on Wednesday: "If it's up to me, I'm playing.

"But I think there's a few other people in that conversation," he told Channel Nine.

"It's not up to me. I'll get there on Friday and see how it pulls up over the next few days."

AAP