The Italian has proved to be a bit of a nemesis on Tour for the Sydneysider, who had gone down twice in their previous meetings.
Sonego first triumphed over Duckworth in 2021 at Wimbledon when he won 6-3 6-3 6-4 in the third round.
Then came the defeat also on grass - at Eastbourne International - in the round of 32 in 2022 when Duckworth lost 4-6 7-6 (7-5) 7-6 (7-1).
So the 7-5 6-3 victory on Thursday (AEST) in the ATP-250 event would have been coupled with sweet revenge and a tinge of relief, ahead of next week's US Open at Flushing Meadows.
With his world ranking of 79, Duckworth has qualified directly into the main draw for the last grand slam of the year.
The 34-year-old needed one hour and 44 minutes to dispatch of Sonego, breaking serve twice in the match and fending off all three break point opportunities.
Duckworth will now meet the winner of No.15 seed Fabian Marozsan and American wildcard Martin Damm for a place in the semi-finals.
Earlier, Rinky Hijikata's bid to make the last eight came to a crushing halt when the Australian was beaten 6-1 6-1 by Benjamin Bonzi.
It was a 'bullseye' performance from the Frenchman, who didn't miss much in a 6-1 6-1 demolition that lasted just 57 minutes.
Bonzi won 96 per cent of points on first serve and converted five of seven break point opportunities.
In some of the other results, top British player and No.4 seed Arthur Fery made light work of qualifier Mees Rottgering to progress with a 6-3 6-3 win.
But the tournament is over for No.7 seed Stefanos Tsitsipas, who was beaten 6-3 7-6 (7-1) by American Aleksander Kovacevic.
6°C