Long-time rivals on the ITF Circuit, this was the first time the players had met at a WTA event, and it was Han that reacquainted herself the quicker. However, after dropping the first set Duan slowly came back into contention in the second, pinching it after getting the better of a flurry of late service breaks.
She rode this momentum into the decider, opening up an early lead before reeling off the final three games to close out a 3-6, 6-4, 6-2 victory.
"It's been a while since I last played her so it took me some time to get used to her game, especially because she's a lefty," Duan said. "I lost the first set but changed strategy in the second and third and it worked.
"I'm happy with my performance today. And felt quite lucky that I won in the end. She moves very well on court. It's quite difficult to play her."
Elsewhere, there were mixed fortunes for the Chinese contingent; Liu Fangzhou provided further home cheer with a 6-4, 6-3 win over Jang Su Jeong, while Misa Eguchi ended the run of qualifier Zhu Lin, 6-4, 6-2.