After cruising through the first set, 6-1, Stosur watched on as Schmiedlova began playing almost flawlessly, the WTA Rising Star jumping out to 3-0 in the second set and stretching that lead to 5-2.
But the No.2-seeded Stosur reeled off the last five games in a row to close it out, 6-1, 7-5.
"It wasn't ideal conditions today - it was obviously tricky when we walked out and then had to go back inside a little while because of the rain, and the court was a little bit slippery, too," Stosur said.
"But they did a great job to make it playable, and it was nice that the rain stayed away so we could play the match in the end. It ended up being a very good match and I'm very happy to be in the final."
How did the Australian, a former World No.4, dig herself out of that deep second set hole?
"Basically I thought I was going to be able to have more chances to break her," she said. "I was able to break her a couple of times in the first set, and I knew if I kept playing the way I was, I would have more opportunities. It's not like she was holding serve easily - I got to 30-all and deuce on most of her service games in the second set, and I knew I would eventually get more chances to break."
Stosur has now won 11 of her last 13 matches on clay and is chasing her eighth career WTA title.
"I don't think you can ever expect to make it to a final, but I hoped I would," she said.
"I hoped I'd play well and play the tennis I'm capable of, and I've been able to do that here."
"I don't think I've played Karin, and I've played Sara many times - I'm sure they'll have a tough match," Stosur said. "Whoever I play, it'll be tough. It's hard to play twice in one day, but sometimes it also helps you play yourself into your best form, so I know I'll just have to play my best tomorrow."
? WTA Gastein (@WTAGastein) July 25, 2015