Starc is a big doubt for the fourth test against England with a bruised heel and although scans have cleared the pacer of serious injury, the selectors will take a cautious approach with the Ashes won and the four-test tour of South Africa coming up.
"It's a funny kind of injury," pace bowler Cummins said on Saturday. "It's not super common, but if it's not treated well it can drag on for a very long time.
"It's a bruise pretty much where you've got to walk all day and bowl. I'm sure they'll come to an agreement and if he knows he's not right, he'll put his hand up."
Starc, the top wicket-taker in the series with 19 victims, bowled with the heel problem in the third test at the WACA as Australia wrapped up an innings and 41-run win for a 3-0 lead.
The left-armer did not participate in Australia's training session at the Melbourne Cricket Ground on Saturday and sported a large compression sock on his right ankle.
Cummins suffered a similar injury following his test debut in 2011 and was out for more than four months.
"I chatted to him about it... it's one of those ones where there's no way around it. You can't strap it differently, you can't bowl off the other foot or anything. It's hard to hide," Cummins said.
"So (you have to) try and get it early enough and not try and really, really damage it. It can be a long process trying to get it right. He knows that, the staff know that and I'm sure they'll work it out."
Reserve seamer Jackson Bird is likely to step in if Starc is ruled out.
"I hope for Mitch's sake his heel's not too serious and he does get up," Bird said. "But it'd be unbelievable to play an Ashes Test on Boxing Day. Either way I'll be ready."
The hosts will also have wicketkeeper Tim Paine joining the squad on Sunday after he stayed at home in Tasmania due to his father-in-law being hospitalised following a stroke.
First Published: December 23, 2017, 4:31 PM IST