The fluency, consistency and confidence Azarenka showed in New York were strangely missing on Wednesday but the No.10 seed was most disappointed about the mental side of her game.
“The lesson I need to learn is that sometimes when things don't work for me, the way I was playing today… was to be willing to adjust a little bit more and not think at the end of the match to finally start changing my game,” she said.
“I felt like I was trying a lot, trying different things, but today things were not working. I felt like nothing really was working, but I still had to find a way to win, and I didn't.
“So it's a lesson for me to learn how to be more courageous, to go for more. And I will learn it, for sure.”
Schmiedlova was ranked as high as No.26 in 2015 but had knee surgery after Wimbledon in 2019.
A nasty fall early in the second set gave Schimiedlova a scare but the 26-year-old recovered and maintained her poise as she wrapped up one of the biggest victories of her career.