Test captain Cummins is nursing a lumbar bone stress issue in his lower back. He's been out for the count since the West Indies Test series in July and with the first ball of the Ashes opener set to be bowled just six weeks from now in Perth, there is concern.
Cricket Australia are yet to provide any update on their superstar seamer, adding further fuel to the rumour mill. But Starc is keeping close tabs on his buddy.
"He's in good spirits," the 35-year-old told ESPN
"He's ultra-positive as always, and there's still some weeks to go before we get to Perth for the Test prep. So we'll see where that lands. Hopefully, we see a lot of him through the summer, and we'll see where we get to in Perth."
Starc also revealed that given the closeness of the Test bowling unit - which also features the metronomical duo of Josh Hazelwood and Scott Boland - he knows what Cummins is capable of off a short runway.
"Playing with Pat and being close with Pat, he doesn't need much," he continued.
"Whether he bowls three warm-up balls and the first over the game, he's on the money, he just knows when to switch on or how to switch on really quickly. So what it looks like for him in his prep, it's going to be certainly different to what mine feels and looks like, and that comes with experience and age.
"Having spent so much time with Josh [Hazlewood] and Pat and myself and Scotty [Boland], we all prepare slightly differently. We all feel like we need different things. I feel like at times I need to bowl more around preparation stuff, whether it be training or after layoffs."
Veteran Steve Smith is in pole position to take over as captain should he be required and Starc has full confidence in him.
"We've got a group of us that have played cricket with Steve as captain anyway," Starc said.
"And then the times that he's filled in over the last few seasons for Pat, whether it be for personal reasons, for illness or for injury, it's an easy transition for Steve. He's obviously a very experienced cricket brain and thinks heavily about the game, and we have a team of experienced guys that can give their two cents worth along the journey as well."
The first Ashes Test gets underway on 21 November in Perth, with the second scheduled for The Gabba on 4 December.