The 23-year-old Popyrin, ranked at 90 on this planet, got here via 6-7 (5/7), 6-3, 6-4 after two hours and 36 minutes on court docket to assert a second profession title so as to add to his 2021 Singapore victory.
Three-time main winner Wawrinka, 38, hoped to seize a seventeenth profession title however first since Geneva in 2017.
Wawrinka recovered from 3-5 down within the opening set earlier than claiming the tie-breaker.
Popyrin, 15 years Warinka’s junior, levelled by pocketing the second set and was a break forward within the first sport of the decider which he instantly handed again.
The younger Australian twice required help from the coach within the third set however carved out the important thing break within the ninth sport earlier than serving out for victory.
Regardless of defeat, former world quantity three Wawrinka will return to the highest 50 subsequent week having fallen out of the highest 300 after present process two surgical procedures on his toes in 2021.