Adelaide - World No 1 Ashleigh Barty will warm up for the Australian Open with a final at the Adelaide International after a 3-6, 6-1, 7-6 (7/5) comeback win over Danielle Collins on Friday.
The Australian, whose matches have been 5 000-strong sellouts all week at Memorial Drive, will face Dayana Yastremska on Saturday for the title.
Ukrainian teenager Yastremska defeated her third top-20 opponent in a row with a 6-4, 7-6 (7/4) win over Aryna Sabalenka of Belarus.
The men's final will be a contest between in-form Andrey Rublev and South African Lloyd Harris, who defeated fellow qualifier Tommy Paul 6-4, 6-7 (3/7), 6-3.
Rublev is the first man since 2004 to play finals in the first two weeks of a season after the Doha champion outlasted Canadian Felix Auger-Aliassime in a 7-6 (7/5), 6-7 (7/9), 6-4 thriller which took a shade over three hours.
Auger-Aliassime, 19, saved two match points in the second set and grabbed a 3-0 lead in the third before his Russian opponent fought back.
"This match was unreal," said world No 18 Rublev.
"I don't know how I won. I lost myself a bit when I trailed 2-0 (third set). I told myself to start again, breathe and fight for every point."
Barty took a while to get going against 27th-ranked American Collins who dominated the opening set.
But the second was a different story, with top seed Barty quickly finding her game to level the match.
The third set went to a tie-break after the players traded breaks of serve.
Barty lost a 4-2 lead in the breaker, but won on her second match point as a Collins return clipped the top of the net.
"I worked hard tonight, and we got the result that we're after," she said. "I felt I had a lot of clarity with what I wanted to do.
"Danielle has the ability to take the match out of your hands a little bit."
Barty beat Yastremska in their only previous meeting last March in Miami.
"Dayana brings a lot of variety to her game, she's an exceptional ball-striker. All of these young girls are hitting so hard, it makes me feel old," the 23-year-old said.
Yastremska thrashed world number 20 Donna Vekic in the quarter-finals and was a set up against former Australian Open winner Angelique Kerber when the German retired from their last-16 match with back pain.
Ranked 24th, Yastremska is bidding for the fourth title of her career.
Harris, 22, will be competing in his first ATP final.
"To be honest, it doesn't seem real now," he said. "It was a tough match for both of us, we were both nervous.
"I tried to lift my level, but it was a difficult match all in all, one of those days where I felt like I wasn't at 100 percent.
"I wasn't playing my best, but somehow I managed to battle through it - that was amazing for me."
Harris needed two hours and 11 minutes to advance past the American, firing 13 aces and breaking four times while losing his own serve twice.
Results on day six of the ATP-WTA Adelaide International at Memorial Drive:
Lloyd Harris (RSA) bt Tommy Paul (USA) 6-4, 6-7 (3/7), 6-3
Andrey Rublev (RUS x3) bt Felix Auger-Aliassime (CAN x2) 7-6 (7/5), 6-7 (7/9), 6-4
Dayana Yastremska (UKR) bt Aryna Sabalenka (BLR x6) 6-4, 7-6 (7/4)
Ashleigh Barty (AUSx1) bt Danielle Collins (USA) 3-6, 6-1, 7-6 (7/5)