
The four-times Grand Slam champion came into the title match at the National Tennis Centre after a hard-fought semi-final win over Alex de Minaur on Tuesday, during which he struggled with physical problems caused by a stomach bug.
There were no signs of discomfort in his first meeting with 19-year-old Tien, however, as Sinner settled into the match with a break in the opening game and looked solid throughout to take the first set with a hold in the final game.
Tien, playing in his first final and bidding to become the youngest American ATP Tour champion since Andy Roddick in 2002, twice earned breakpoints in the second set but Sinner fended them off and built a 4-2 lead.
The 2023 champion then sealed the win to became the second man to claim multiple titles at the ATP 500 tournament after Novak Djokovic (2009-10, 2012-15).