The opener made the one half-century of the match as Australia came out on top
The 27-year-old McDermott was one of two changes to the side which clinched the T20 World Cup in the UAE under the recently-departed Justin Langer.
He backed up his form as top run scorer in the BBL with the Hobart Hurricanes by registering a game-high 53 from 41 balls.
While he said it was relief to bring up the milestone score, he conceded that he remains a long way off cementing a more permanent spot.
“With Davey away, I’m sure he’ll come back into the side pretty nicely,” McDermott said. “I haven’t thought too far ahead but it was nice to get that opportunity tonight.
“David Warner and Aaron Finch did an excellent job up there in a World Cup-winning side not so long ago It would be nice to keep scoring runs and put my name up there but I don’t feel like I’ve cemented it.”
In his previous 17 games since his debut in 2018, McDermott had been a bit-part player but he looked a cool customer while the more experienced pros around him lost their heads.
Finch, Steve Smith, Glenn Maxwell and Matthew Wade all fell cheaply with Marcus Stoinis (30) and debutant Josh Inglis (23) the only other two Australians to make double figures. But McDermott’s haul, which included three sixes, helped guide Australia home.
“I don’t remember batting as well as I have at the moment,” he said. “I do feel that I’m in pretty good form but with a lot of work to do as well.
“It’s exciting times and hopefully I can keep improving around this group because there’s some really experienced players to learn off. It was nice to have Finchy at the other end. He’s a very cool head and experienced player to lean on.”
Australia return to the SCG on Sunday before travelling to Canberra.