Petra Kvitova constructed a 6-7 (6/8), 6-4, 6-3 comeback over Madison Keys on Saturday to reach her first final at the ATP and WTA Cincinnati Masters.
The two-time Wimbledon winner who played the final four here in 2012 and 2018, will face either French qualifier Caroline Garcia or sixth seed Aryna Sabalenka in Sunday's final.
"It was an incredible match, I expected it to be tough - but not this tough," the 32-year-old said as she makes a return to the ranking top-20.
"I just kept going and tried to break here (after losing the first set). I played more calmly and waited for my chances, which came.
"I'm happy I made it somehow. I don't care about the ranking but the important thing is to be in another final.
"That's why I play tennis, to compete for the trophies. I got emotional at the end, the match was mentally so tough."
Kvitova, ranked 28th, lost the opening set after nearly an hour to her American opponent, the 2019 Cincinnati champion.
But the Czech struck back with two breaks in the second set and began the third with another as she turned the tables for victory in two hours, 20 minutes.
Kvitova recovered from 0-40 down in her last service game before breaking Keys for victory on a third match point as the American returned wide.
Kvitova was competing in her 63rd career semi-final and moved into her 12th final at the Masters level.
She now stands 5-4 in her series with Keys.