Britain's Andy Murray proved too strong for American Mardy Fish in the searing Cincinnati heat as he reached the final of the Masters 1000 event.
Fish went into the match as one of the form players of the summer but was always struggling to stay with Murray.
The Scot edged the first set and battled his way through a second set of six breaks to win 6-3 7-6 (10-8).
Murray will face world number one Novak Djokovic in Sunday's final.
The women's final will be between world number seven Maria Sharapova and Jelena Jankovic, the world number 14 from Serbia.
Sharapova came from a set down to beat second seed Vera Zvonareva 2-6 6-3 6-3. The Russian is chasing her second title of the year, after winning in Rome in May.
Jankovic hasn't won a WTA Tour title since March 2010, and faced few problems in beating Andrea Petkovic of Germany 7-6 (7-4) 6-1.
Djokovic progressed, and improved his record for the year to 57 wins and one loss, after Tomas Berdych retired with a shoulder injury in their semi-final having dropped the first set.
Top seed Djokovic, who also played with tape on his right shoulder, said: "I know he struggled a little bit with a shoulder injury. We have a similar thing, he just has a more serious injury."
Murray and Djokovic will meet for the 10th time at 1730 BST on Sunday, with the Serbian leading their head-to-head 6-3.
"I think it would be perfect preparation to play him before the US Open, to see what I need to work on," Murray said after his semi-final win.
Murray, 24, showed signs in the opening set of getting back to somewhere near his best as he became the first man this week to break the Fish serve in moving 3-1 clear, converting his fifth break point of the game.
The Briton saw off three break points on his way to closing out the set and looked well on course when he broke at the start of the second.
It merely heralded a succession of breaks, however, Murray going ahead three times only to be repeatedly pegged back by Fish as his first-serve percentage dipped below the 50% mark.
Both men were now struggling physically, with Fish appearing to wilt in the brutal conditions and Murray repeatedly trying to stretch out his hamstring, but the American was not in the kind of form to really punish him.
The Fish forehand was proving particularly wayward, and two set points slipped by in game 12 as it came down to a tie-break.
This time it was Murray who fought his way back from a deficit and he looked to have clinched it on his second match point, only for Hawkeye to rule his forehand had missed the line by a hair's breadth.
There was to be no deciding set though as the Briton made no mistake when a third opportunity presented itself, sealing victory after a gruelling two hours and 18 minutes.
"I was struggling physically in the second set - it was hot but that's not an excuse," said Murray.
"My legs were feeling tired. It was the conditions. I need to get stronger. This is the first tough match I've played for five or six weeks. I need to get some more endurance in me before the US Open."
The final Grand Slam tournament of the year begins in New York on 29 August.