Alex Robertson (left) is protected by teammate Harry Souttar during a scuffle against Ecuador
The Sydney-raised 19-year-old has played junior football for England, but looks set to commit himself to Graham Arnold's side.
His father Mark played for Australia in 2001, as did his grandfather in 1984, with both in the Sydney crowd watching.
The midfielder, who has yet to make his senior debut for Pep Guardiola's side, came on with 15 minutes left. He played a part in Australia's final goal of a 3-1 win, but was also involved in a late scuffle.
Germany-based Jackson Irvine, Sparta Prague striker Awer Mabil and Hearts' Garang Kuol all got on the scoresheet, in Australia's first match on home soil since their run to the last 16 at the 2022 World Cup.
In a game seen as the beginning of a new cycle with qualification for the 2026 World Cup later this year and the Asian Cup looming in 2024, Arnold also handed a debut to Melbourne City's Aiden O'Neill, who played the entire game and impressed.
"I'm so pleased for the boys, some of the young guys have played and were unbelievable," said Australia's Leicester City defender Harry Souttar.
"Aiden O'Neill making his debut, you're not going to get many better debuts than that. Robbo (Robertson) coming on, Garang. The future is really bright for us."
"Robertson's got that bit of bite and we love that, it's what we're all about," he added.
Defeat was a bitter pill for the Spaniard Sanchez, who took charge for the first time since being appointed this month, replacing Argentine Gustavo Alfaro who left after Ecuador were eliminated in the World Cup group stage.
Irvine put the home side in front after 12 minutes, side-footing home from close range.
But the visitors levelled 11 minutes later through Felix Torres, who climbed above the defence to powerfully head home.
An error by Bayer Leverkusen's Piero Hincapie on the edge of the box saw them go behind again, the defender losing possession to Mabil who drilled the ball into the roof of the net.
Both teams threatened in the second half before Kuol made sure of the win with six minutes remaining.
The two sides meet again in Melbourne on Tuesday.
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