CINCINNATI, Ohio (AFP) - Andy Murray beat Carlos Moya 2-6, 6-3, 6-1 to complete a spirited fightback and move into the semi-finals of the Cincinnati Masters here on Friday.

Murray's success took just over 90 minutes as the eighth seed turned around a desperate situation, down a set and a break in hot summer conditions.

On Saturday, the Scot will face either German Philipp Kohlschreiber or Croatian 16th seed Ivo Karlovic, who stunned world number one Roger Federer in the third round.

As a result of that upset, Rafael Nadal, facing a later quarter-final against Nicolas Lapentti, could take over the number one ranking from the Swiss if he can lift the trophy at the weekend.

Murray will be playing on Saturday in the fifth Masters semi of his career, having never gotten past that stage.

"It was really tough at the start," said the winner. "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.

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 to improve to 33-12 on the season.