Then he sealed Australia's sixth consecutive World Cup finals appearance.
But his teammates never doubted his value, or ability to step up.
Duke, who for a second consecutive window was left out of Tony Popovic's squad only to earn a late reprieve, is soaking it all in.
The veteran striker came off the bench in the 1-0 win over Japan that effectively sealed automatic qualification for the 2026 tournament.
Then Popovic called on Duke to start against Saudi Arabia in Jeddah, where Australia only needed to avoid defeat by less than five goals.
Australia conceded the opener but in the 42nd minute, Duke teed up Connor Metcalfe to score the equaliser.
Three minutes after halftime, the much-maligned striker glanced home a header to put Australia in front with his first goal since January 2024.
"I wasn't even supposed to be here, to be honest," Duke said.
"Mat Leckie got injured, and I was a late call-up.''
He joked: "Got the voodoo doll out and maybe injured Leckie. Nah, kidding, sorry, mate.
"But it feels good, and probably a good way to silence some of the keyboard warriors as well. Feels good."
Duke had previously been open about critics on social media coming for him after he missed chances in Australia's Asian Cup quarter-final exit last year.
Winger Martin Boyle was singing the praises of hard-working Duke, one of the heroes of Australia's golden run at the 2022 World Cup.
"Absolutely delighted for him," Boyle told AAP.
"Obviously, as footballers, you're open to a lot of criticism, but for Dukey, he just powers through. He comes up with some massive goals.
"Obviously he was disappointed not to be selected in the initial squad. But he's also come back, he's kept his head down, and he's changed the game against Japan.
"He took his chance and his opportunity tonight with a goal and an assist.
"I love playing with him, and I have done for many years, and everything that he's given for the country. He's a top-class striker and hopefully he can keep going."
Duke relished Australia's turnaround in qualifying after Popovic took over from Graham Arnold, who resigned after a loss and draw in his first two games of the campaign.
"It feels damn good," Duke said.
"Not the best start (to qualifying) to be honest, and to get us here, into automatic qualification, we haven't done that for a while, just feels unbelievable."
Now 34, Duke knows he will have to kick up a gear to retain his spot ahead of next year's tournament in north America, especially with young strikers like Mo Toure waiting in the wings.
"All I can do is take the opportunities when they're presented to me, do well at club football, and hope I just keep doing well," he said.
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