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The fourth-seeded De Minaur led the eighth seed 2-0 in the first set when his Kazakh opponent retired due to a right ankle injury he suffered in his semi-final.
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"I knew I'd put in a great pre-season. I felt good and ready to compete," the 21 year-old said. "I gave myself the best possible chance to go deep in this tournament."
De Minaur, whose previous titles came in 2019 at Sydney, Atlanta and Zhuhai, now heads to Melbourne for the Australian Open which starts on 8 February.
"I'm looking forward to returning to Australia, where I hope to have a good Aussie summer in front of a home crowd," the world number 23 added.