World number one Ashleigh Barty has reached her sixth final of 2021 in Cincinnati, while Andrey Rublev upset top seed Daniil Medvedev to progress to the men’s final.
Australian Barty, who won Wimbledon in July for her second Grand Slam title, overcame Angelique Kerber 6-2 7-5.
Rublev then came from behind to defeat Russian compatriot Medvedev for the first time, winning 2-6 6-3 6-3.
In doing so, the fourth seed reached his second ATP Masters 1000 final.
The 23-year-old, ranked seventh in the world, will face Germany’s Alexander Zverev on Sunday.
It was a semi-final to forget for Medvedev as the world number two collided with a courtside TV camera during a rally with Rublev.
The 25-year-old was a set up in the match and shoved the lens with his foot before complaining to the umpire that he “could have broken my hand”.
Medvedev eventually needed a medical time-out for treatment on his left hand.
Two-time Grand Slam winner Barty, 25, has not yet dropped a set in Cincinnati and has reached the tournament’s final for the first time.
She will play Switzerland’s JilTeichmann on Sunday, after she defeated Czech fifth seed Karolina Pliskova 6-2 6-4.
It will be Teichmann’s first WTA 1000 final, and follows wins over four-time Grand Slam champion Naomi Osaka and Olympic gold medallist Belinda Bencic in the earlier rounds.
In the other men’s semi-final, Olympic champion Zverev beat Greece’s Stefanos Tsitsipas 6-4 3-6 7-6 (7-4) in an engrossing encounter that saw the 24-year-old’s unbeaten run extended to 10 matches.
In a contest lasting two hours and 41 minutes, the third seed admitted to feeling unwell after winning the first set.
“In the middle of the second set I felt low energy and my stomach wasn’t great,” Zverev told the ATP website. “I broke him at 4-2 in the third and went outside the court and did my thing.
“I started to feel better, the doctor came out and gave me a little medicine and my stomach started to calm down a little. The energy came back but I think that was also adrenaline.”
Meanwhile, Britain’s Emma Raducanu has reached the final of the second-tier WTA Challenger event in Chicago.
The 18-year-old, who reached the last 16 at Wimbledon, beat American Claire Liu 7-6 (7-3) 4-6 6-1 and will meet Clara Tauson of Denmark in Sunday’s final.