Nick Kyrgios and Grigor Dimitrov will meet in the Cincinnati Open men's final while Garbine Muguruza will face Simona Halep in the women's final.
Australian Kyrgios beat David Ferrer 7-6 (7-3) 7-6 (7-4) while Bulgaria's Dimitrov advanced against John Isner 7-6 (7-4) 7-6 (12-10).
Spain's Muguruza eased past top seed Karolina Pliskova 6-3 6-2, while Halep beat Sloane Stephens 6-2 6-1.
Romanian Halep will become world number one if she wins the tournament.
"I think it's something special to get number one in the world," said Halep, who would move above Czech Pliskova.
"Everyone can get to number one now.