Grigor Dimitrov reached his first ATP Tour final after overcoming John Isner and will play Nick Kyrgios in Sunday’s showdown at the Western & Southern event in Cincinnati.
Seventh seed Dimitrov needed just over two hours in a gruelling contest that yielded no breaks of serve to edge past the big-serving American 7-6 (7-4) 7-6 (12-10).
Isner, who conceded just eight points from his six service games during the opening set, missed two chances to break when leading 3-2 and 40-15.
In the opening tie-break, the decisive moment came on the fifth point when the 26-year-old Bulgarian secured the only mini-break.
The second set followed a similar pattern, with the sole break point arriving in game 10 when Dimitrov was briefly offered a first match point.
But the 32-year-old from North Carolina survived and then watched three-set point opportunities come and go, before Dimitrov finally put the match to bed on his fourth match point.
Kyrgios now stands his way of a maiden ATP title after the Australian beat former world No 3 David Ferrer in another double tie-breaker 7-6 (7-3) 7-6 (7-4).
Kyrgios, who has struggled with hip and shoulder injuries the past two months, showed grit to advance past the lively Spaniard.
“He was a nightmare to play, especially because I’m a tall guy and he’s not the tallest guy,” Kyrgios said.
“I didn’t play my best tennis. I’m just really proud that I managed to scrap out the win.”
Coverage of the Western & Southern Open wraps up with Sunday’s final from 9pm on Sky Sports Action