Defending champion Karolina Pliskova saved a match point before prevailing in an epic slugfest with Naomi Osaka, while Madison Keys pulled off an escape of her own in the other semi-final in the Brisbane International on Saturday.
Pliskova and Osaka served 29 aces between them and were often locked in fierce baseline rallies before the second-seeded Czech won 6-7(10) 7-6(3) 6-2 in two hours and 48 minutes.
Osaka had survived three consecutive three-setters en route to the semi-finals and Pliskova's title defence appeared over with the Japanese serving for the match at 7-6(10), 6-5.
The Czech then roared back into the match, earning her first break of Osaka's serve to force a tiebreak and fired eight of her 15 aces in the final set, while saving all six breakpoints.
Pliskova will play Keys in Sunday's final hoping to add to her 2017 and 2019 crowns.
Eighth-seeded Keys came from a set and a break down against 2011 champion Petra Kvitova to win 3-6, 6-2, 6-3 in the duel between two of the WTA's biggest hitters in the first semi-final.
Kvitova fired eight winners to claim the opening set before the American fought back and won six straight games to take the second set.
Keys held her nerve in the decider which saw five breaks in the last six games and completed her turnaround winning 12 of the final 15 games.
"I'm very happy. I'm very tired," the American said after her fourth victory in seven meetings with Kvitova.
"It's always great to start the year playing great tennis. The third set was back and forth (but) I think I played a pretty high level."
