Novak Djokovic kept his win streak alive at the Paris Masters on Thursday, but there was defeat for Roger Federer at the hands of big-serving American John Isner.
Rafael Nadal and Andy Murray also reached the quarter-finals, but in contrasting styles.
World number one and defending champion Djokovic went through to the last eight in the final tournament of the ATP’s regular season with a 6-3, 7-5 victory over Gilles Simon that took his unbeaten run to 19 matches.
It was far from being the world number one’s most commanding performance of late as he struggled with his serve, but it meant he has not dropped a set since the US Open final against Federer in early September.
He has now won 26 sets in a row, taking him past his own previous best of 24 sets which he achieved in early 2014.
The Serb, who has won three of the four Grand Slam titles and five of the eight Masters 1000 series titles so far contested this year, dropped serve five times against the wily Frenchman, four coming in the second set.
But on each occasion he immediately struck back to prevent Simon from gathering any momentum.
The 10-time major tournament winner said his struggles on serve had been frustrating.
“I can assure you, losing four service games in a set, I don’t think that has happened to me,” he said.
“I’m not a serve specialist, but I think I have a solid serve and it hasn’t happened for a long time.
“It wasn’t pleasant, but I knew that I have a good return. I was feeling the ball very well from the back of the court.
“So that kind of was a positive to that, knowing that I can break him most of the time. That was the kind of mindset.”
Djokovic will next play fifth seed Tomas Berdych of the Czech Republic who eased past an injury-hampered Jo-Wilfried Tsonga 6-3, 6-4 for a place in the semi-finals of a tournament he has won three times previously, including the last two years
Federer was shocked to find himself leaving for home without once having dropped his serve as Isner typically won on two tie-breaks 7-6 (7/3), 3-6, 7-6 (7/5), hammering down 27 aces in the process.
– Nadal saves match point –
The Swiss legend agreed that Isner had served superbly on the big points.
“He’s got the size, got the power, got the angles,” the 34-year-old said.
“I thought he did very well today when he needed it. The breakers, he served great. Those are the ones he needed. Yeah, that was the difference.
“It’s tough to get out of the tournament not having lost your serve, you know, but that’s how it can go against John.”
Federer, who won his hometown tournament in Basel last weekend, will now switch his focus to London and the ATP World Tour Finals.
Isner will play David Ferrer for a semi-final spot after the Spanish eighth seed outlasted Grigor Dimitrov of Bulgaria 6-7 (4/7), 6-1, 6-4.
Asked where the win ranked in his career best Isner replied: “It’s up there, for sure. I don’t know off the top of my head. It’s certainly top five I would say.
“This is a very big tournament. He’s an incredible player, obviously. My favourite player and the greatest of all time, my opinion. It was a huge win for me. I’m very proud I was able to get it done.”
Nadal saved a match point in the second set tie-breaker against South African Kevin Anderson before prevailing 4-6, 7-6 (8/6), 6-2.
He will next take on French Open champion Stan Wawrinka who beat Victor Troicki 6-4, 7-5.
In earlier action, British second seed Andy Murray set up a quarter-final clash with Richard Gasquet of France by pounding Belgium’s David Goffin 6-1, 6-0 in just 53 minutes.
The match had extra significance in that the two will lead their respective countries at the Davis Cup final in Ghent from November 27-29.
Murray certainly chalked up some psychological points in what was just the second career meeting between the two men.
Gasquet’s win over Kei Nishikori came when the Japanese star abandoned due to back pain while trailing 7-6 (7/3), 4-1.
The Frenchman, whose best showing in Paris Masters was a run into the semi-finals in 2007, said that Murray would present the toughest of challenges.
“He’s one of the best players in the world. He’s extremely difficult to beat every time because he makes few unforced errors,” he said.