According to Ellis, who was quite outstanding with his 4-12 as they trounced Ireland in their opening game in Colombo, Marsh's painful testicular injury left his side sorry for him but, equally, determined not to be disrupted by losing their leader.
It's not clear if or when the 34-year-old will be back in action after he took a blow in the groin in practice that left him suffering internal testicular bleeding, but Ellis is sure the batting riches in the side remain plentiful enough for even emergency recruit Steve Smith to have to fight for a place in the top-order.
"Mitch has been a little bit sore over the last few days, so poor bugger, you don't envy a man in that position," said Ellis.
"Never a great scenario for the team when you lose a captain, but also for the person who goes to bed last night thinking they're not playing and then has to come in.
"But in terms of disruption with the team, we've got the easiest, most easy-going group in the world. Travis Head stepped in as captain and his heart rate probably doesn't get above 25 at the best of times!
"Obviously, we all want Mitchie there, and we love Mitchie leading us. But it wasn't spoken about too much, and we just try to hit the ground running."
Asked about Smith's call-up on standby, the pacer added: "Oh, we actually haven't played a game with him in a long time for Australia.
"He's obviously a gun. He's one of the world's best. But, mate, we've had 18 months and about 20 T20 games leading up to this where we've had a top-order who have absolutely brained it.
"So there's obviously a lot of noise around Steve Smith scoring runs in the BBL, but our top-order is world class. Obviously, we're missing Marsh today, and you throw up a player like Josh Inglis (as opener), so yeah, it's a tricky one.
"It's always going to be tricky when you've got so many good talents and top-order batters. It's hard to squeeze into that top-order."
The best news for Australia, though, was Ellis's performance himself with the ball, as he dared to be different from his very first ball, with his back-of-a-length, slower delivery bamboozling and bowling Ross Adair.
He struck a couple of balls later too with another puzzler, effectively stopping the Ireland innings in its tracks.
Asked whether he was taking the mantle left by the absent 'big three' of Pat Cummins, Josh Hazlewood and Mitch Starc, the modest 31-year-old shrugged: "I don't look at myself as the leader of the attack.
"It means a lot for me to be here in the Australian jersey at a World Cup, that's probably the biggest thing."
