the 20-year-old Thai, the world number seven, came from behind to twin 20-22, 23-21, 21-12 against the home favorite in the women's singles of the Badminton Asia Championships in a match that lasted 1 hour and 16 minutes.
it was her first victory over the world number three since last year when li swept all three of their meetings.
Ratchanok will return home with the US $5,000 (480,000 baht) cash prize from the tournament.