Cincinnati, August 2:

Rafael Nadal marked an historic changing of the guard in tennis with a quarter-final win at the Cincinnati Masters on Friday, ensuring Roger Federer will fall from the summit after more than four years.

The patient Spaniard, who has chased the Swiss for three seasons in a good-natured rivalry, guaranteed he will claim the world number one ranking this month with a 7-6 (7/3), 6-1 victory over Ecuador’s Nicolas Lapentti.

By reaching the semi-finals, Nadal is assured of overtaking Federer on August 18 at the latest. If he can carry on to claim the title on Sunday he can claim number one on Monday.

Federer has held the world number one ranking for more than four years — his reign so far lasting 235 straight weeks. But his hopes of holding off Nadal faced with his third-round loss here to Croatian Ivo Karlovic. “I’m so happy to be getting number one,” said Nadal, the winner of 30 career titles including five grand slams. “I fought hard to get here.”

Nadal will become the 24th player in the history of the ATP Rankings to hold the number one position and the third Spaniard to accomplish the feat, joining Carlos Moya (1999) and Juan Carlos Ferrero (2003). He faces a semi-final challenge against third-seeded Novak Djokovic after the Serb defeated Ernests Gulbis 6-3, 6-4.

At the top of the draw, Andy Murray beat Carlos Moya 2-6, 6-3, 6-1 to

complete a spirited fightback. The eighth-seeded Scot will next play Karlovic, who notched 24 aces in his 7-6 (8/6), 7-6 (7/3) win over German Philipp Kohlschreiber.