Rafael Nadal survived the carnage to advance to the semi-finals of the Montreal Masters on Friday with a 5-7 6-4 6-3 defeat of long-time rival Roger Federer.
The win keeps Nadal on track for a possible rise to second in the world behind Novak Djokovic if he can win the event and claim his third hardcourt title of an unblemished season on cement.
Federer won the opening set but could not hold off his Spanish opponent.
"Credit to him for hanging in and getting back some trough shots," said the five-time champion. "I have some disappointment, I could have played better late in the second and early in the third.
"But my tactics were working most of the time. I did pretty well.
"I served well for most of the match, but when I didn't he was able to step it up - that was the match right there."
Nadal improved to 21-10 against his top rival, including wins in all of their three matches this year.
The 17-time grand slam champion Federer will fall out of the top five for the first time in well over a decade after he could not maintain momentum from a near-perfect first-set effort.
American John Isner stunned record-seeking Djokovic 7-6 (7-5) 3-6 7-5 to set up a semi-final with Argentine Juan Del Potro.
Djokovic had been bidding to become the first man to win all nine Masters 1000 titles during a career - but to do that he needed to win Cincinnati.
Isner erased that possibility with a 15-ace performance in just over two and a half hours to move into the final four on home hardcourt.
"I just played a very bad match overall," said Djokovic. "Terrible match, from beginning to end.
"Except for the start of the second set I was a different player totally. I wasn't able to capitalise on my opportunities, but that's the way it is."
Second seed Andy Murray followed Djokovic out, losing 6-3 6-4 to Tomas Berdych, as he fell to the Czech for the second time this season.
Murray managed 10 aces but couldn't break on any of his four chances.
"The court was lively today. It was bouncing pretty high and it was quite tough to control the ball. I made too many errors," said the US Open champion, who now heads to New York to work on his game in the 10 days remaining until the August 26 start.
