With Socceroos coach Tony Popovic watching on at Campbelltown Sports Stadium, Duke did his chances of World Cup selection no harm when he opened the scoring for the Bulls on Saturday.
The energetic forward, who got through 54 minutes of gametime, was a menace for City's back four who struggled to contain Macarthur's aggressive forward line.
A 40-metre curler from Luke Brattan and another long-range effort from Anthony Caceres, who toyed with the City defence throughout the evening, added to the scoreline.
Luke Vickery, Dean Bosnjak and Harrison Sawyer further boosted Macarthur's lead in the second half in a win that moves Mile Sterjovski's side up to third, just two points off table-topping Auckland.
Duke put the Bulls ahead after just six minutes when he made a trademark run towards the near post, lost German Ferreya and tucked in.
Then three minutes later Brattan joined the action, shooting from distance when he spotted Patrick Beach off his line to put the Bulls 2-0 up.
A 24th minute Medin Mehmeti header was fumbled over the line by Macarthur goalkeeper Filip Kurto to briefly bring City back into the game.
But any sense of a fightback evaporated when Caceres was allowed to run towards City's retreating defence and unleash a shot from distance.
Brattan did not return after halftime after falling awkwardly while challenging for a ball.
But even without their skipper and Duke, who was replaced by Sawyer, the Bulls didn't take his foot off the gas.
Vickery dispossessed Ryan Teague as he tried to play out of his own half and combined with Sawyer before lashing past Beach.
Bosnjak burst through some lacklustre defending to make it five and City looked like they were ready to throw in the towel.
Substitute Marcus Younis, who joined City on loan this week, netted a well-taken strike in the final quarter of an hour.
But Macarthur had the last laugh when Sawyer, who had been in a running battle with Samuel Souprayen, scored in added time to take his side's tally for the night to six.
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