Top seed Novak Djokovic breezed through his third round match on Thursday but world No. 2 Rafael Nadal was pushed to the limit before he reached the quarter-finals of the Cincinnati Masters.
Nadal extended his perfect record against Fernando Verdasco but needed three tiebreak sets to outlast his fellow Spaniard 7-6 (7/5), 6-7 (4/7), 7-6 (11/9) while world number one Djokovic routed Czech Radek Stepanek 6-3, 6-3 in their centre court match.
The top three in the men's draw moved on Thursday as third seeded Swiss star Roger Federer also advanced to the quarters by thumping American James Blake in the evening match, 6-4, 6-1.
It may not have been his best tennis but Djokovic beat qualifier Stepanek to improve his record this season to a brilliant 55-1. He is a perfect 31-0 in hardcourt tournaments.
"It was a very slow kind of ugly match," Djokovic said. "There are days like this where you don't feel like playing. But I hate losing, so I need to win. That's what makes me motivated."
Djokovic won 71 percent of his first serve points compared to just 37 percent for Stepanek.
Federer improved his career record against Blake to 10-1 as the Swiss dominated with his serve, spending a scant 54 minutes on the court.
In contrast, the 25-year-old Nadal needed three hours and 37 minutes to beat Verdasco.
"The truth is that I am very happy," Nadal said between singles and doubles matches. "Very content with the victory. It was a tough match for both of us."
The second-seeded Nadal improved to 12-0 lifetime against the unseeded Verdasco, who committed 41 unforced errors to 31 for Nadal.
"You enjoy always a good match," Verdasco said. "But when you lose in this way, of course it's not easy. You have it so close. Tennis is like that."
Nadal hit fewer winners than Verdasco - 29 versus 48 - but was more consistent with his mixture of shots and had just two double faults compared to seven for his opponent.
For the second consecutive match, Nadal played with two fingers on his right hand bandaged after he burned them while reaching for a hot plate at a restaurant earlier this week.
Nadal next faces American seventh seed Mardy Fish, who outlasted France's Richard Gasquet, 7-5, 7-5.
"I'm very happy I'm through and I'm in the quarter-finals," said Nadal, who lost his doubles match later in the day. "I need to spend hours on court but I would like to have one hour less than what I have."
Fish has dropped all six career matches against Nadal dating back to 2006.
"Just off the top of my head I will be aggressive," Fish said. "I'm not a counterpuncher.
"If you're not going to get up for playing Rafa Nadal in the quarters of a huge tournament like this, then you've got issues."
In other men's third round matches on Thursday, Czech Tomas Berdych beat Nicolas Almagro of Spain 6-2, 6-2, and fourth-seeded Briton Andy Murray defeated American Alex Bogomolov 6-2, 7-5.
In the women's draw, fourth seed Maria Sharapova defeated Russian compatriot Svetlana Kuznetsova, 6-2, 6-3, Aussie Samantha Stosur upset Li Na of China, 6-4, 3-6, 6-4, Andrea Petkovic of Germany defeated Czech Petra Kvitova 6-3, 6-3 and second seed Vera Zvonareva routed qualifier Petra Martic, 6-2, 6-2.
Sharapova easily won the matchup of Russian former US Open champions. Kuznetsova took the title in 2004 and Sharapova won two years later.
Sharapova appears to be near the top of her game as she gears up for the US Open, which begins in less than two weeks.
"She's someone who has a tremendous amount of experience and is a really solid player, always dangerous. So, yes, it was a good win," Sharapova said after the match.
Serena Williams withdrew from the event on Wednesday with a toe injury, which allowed Stosur to receive an extra day of rest before facing Li, the reigning French Open champion.
"I wasn't complaining that she pulled out," said Stosur, who has now beaten Li three times this season.