The Frenchwoman broke twice in three chances in the first set, as she never proved troubled thanks to an erratic performance from the aggressive Chinese right-hander.
The wildcard racked up 15 unforced errors to just five winners in the opening set, despite landing over 70 percent of her first serves, and never created a break point chance on return.
Her best chance came in the opening game, where she forced Mladenovic to deuce, but the World No.49 dropped just two points in her other three service games for the set.
The second set proved similar to the first, in that Duan dropped serve relatively early, and proved unable to make up the deficit the rest of the way.
Though the wildcard kept pace after losing serve in the fourth game, saving a break point which would’ve seen her trail 5-1, she was unable to convert in a pair of return games in which she led 0-30 to create a break in the match.
“It’s never perfect, but the composure overall, to be very focused from the first point to the last point, I think I did this really well today,” she added.
“That’s what I wanted to do, going out on the court: really be steady from the first point to the last point. I was efficient on my serve today, and it was very important to get as many returns as possible in the court.”