Andy Murray has beaten Carlos Moya 2-6 6-3 6-1 to complete a spirited fightback and move into the semi-finals of the Cincinnati Masters on Saturday.
The eighth-seeded Scot will test his confidence against the mighty serve of Ivo Karlovic, who notched 24 aces in his 7-6 (8-6), 7-6 (7-3) quarter-final win over German Philipp Kohlschreiber.
On Thursday, the Croatian giant opened the door for Roger Federer to lose his No.1 ranking to Rafael Nadal as he stunned the Swiss in the third round.
Nadal, who faced Nicolas Lapentti of Ecuador later on Saturday, can clinch the top spot on Monday by winning the Sunday final.
Third seed Novak Djokovic was playing good friend Ernests Gulbis in a quarter-final.
Murray's success took just over 90 minutes as he turned around a desperate situation, down a set and a break in hot summer conditions.
The Briton goes in with full confidence after reaching his fifth career semi-final at the elite Masters level.
"I think I can win a Masters Series, and I'd love to do it this week. I played well last week and had a tight match against Nadal.
"This week I'm playing well again. You know, hopefully I can do it."
Murray improved his season mark to 33 wins, 12 defeats.
"It was really tough at the start," he said. "He was serving well, and I threw in a lot of unforced errors. But once I got going, I played really well.
"I've never been to the final of a Masters but this looks like my best chance. I'm playing well enough and can hopefully come through."
Moya, at 31 a decade older than Murray, ran out of puff after his initial fast start.
Murray made his own luck as he saved a pair of break points in the third game of the second set which prevented him falling down a set and a double break.
"To go two breaks down, a set and two breaks down, would have been tough to come back from," Murray said. "But it happens sometimes in tennis."
From that nadir, he went on a tear, winning six of seven games to gain control.
Moya faded in the third set with Murray coming through in temperatures in the mid-30s Celsius.
The Scot seized the final set, racing away to 4-0 and advancing on his first match point.
