Rafael Nadal produced an assured display to beat big-serving American John Isner 6-4, 7-6(0) at the China Open on Friday and set up a semi-final clash with third seed Grigor Dimitrov.
The top-seeded Spaniard eased to his 59th victory of the year, breaking sixth seed Isner at 5-4 and holding his nerve to sweep a second-set tiebreak.
"I think I played a solid match," Nadal said. "I played very well, changing good directions... I think on return I did well.
"It's an important victory for me, of course, against a player that arrived here playing so well, winning two great matches. For me it's an important one and I'm very happy."
Dimitrov had to dig deep after being pushed hard in his quarter-final against Spain's Roberto Bautista Agut, but held out to beat the fifth seed 7-6(5), 4-6, 6-2 in two hours and 29 minutes.
Dimitrov and Nadal have met on nine previous occasions - of which the Spaniard has won eight - but the Bulgarian's only victory over the world number one came in the Beijing quarter-finals last year.
"He is a player that I really like, a good friend on the tour," Nadal added. "I think Grigor is a player always with a great attitude, with a positive character. I'm happy for him that he's having a good year.
"Tomorrow will be a tough one, for sure. He's playing well."
Dimitrov's victory kept him in the hunt for a spot in next month's ATP Finals, and the 26-year-old stayed fifth in the Race to London rankings but has closed the gap on fourth-placed Austrian Dominic Thiem to 440 points.
Australian Nick Kyrgios sent down 12 aces against qualifier Steve Darcis, winning the first set 6-0 and going 3-0 up in the second before the Belgian retired due to injury.
Kyrgios, seeded eighth in China, will face second seed Alexander Zverev in the last four after the German ended Russian teenager Andrey Rublev's impressive run with a routine 6-2, 6-3 victory.
Cirstea downs Pliskova to reach China Open quarter-finals
A ruthless Sorana Cirstea took full advantage of Karolina Pliskova's patchy form at the China Open on Thursday, reaching the quarter-finals as she consigned the recently dethroned world number one to a 6-1, 7-5 defeat.
Czech Pliskova, who dropped from one to four in the rankings last month and had lost to lower-ranked opponents in the last eight of her previous three tournaments, struggled from the outset against the Romanian world number 44.
Putting pressure on Pliskova's serve, Cirstea won six of seven break points and hit 16 winners to score her first win over a top five player in over four years.
"I didn't think about her ranking, I just focused on my game," Cirstea told a news conference after third-round clash.
"I've been playing well lately, it's just that probably results didn't come as quick as I hoped. But I was working well lately... and I always say that hard work will pay off in the end."
Two-times Wimbledon champion Petra Kvitova produced 38 winners as she trounced another former world number one, Caroline Wozniacki, 6-1, 6-4. Wozniacki failed to convert four break points as Kvitova won in an hour and 13 minutes.
Earlier, French Open champion Jelena Ostapenko progressed when China number one Peng Shuai retired with a knee injury while trailing 3-0.
"It's not the result I wanted to have," Ostapenko told a news conference after the match.
"Of course I feel bad for Shuai, and hopefully she can recover and will be fine."
Ostapenko, who next plays Cirstea, added: "Maybe for me, it was a little advantage that I didn't have to play the full match, as I was playing a lot of matches in the last couple of weeks, so I can rest a little bit more."
Caroline Garcia kept alive her hopes of pipping Johanna Konta to the final spot in the season-ending WTA Finals when she defeated fellow Frenchwoman Alize Cornet 6-2, 6-1.
Rublev turns tables to dump Berdych out
Russian teenager Andrey Rublev recovered from a set and a break down to storm past former winner Tomas Berdych and into the China Open quarter-finals on Thursday.
Rublev, who beat the big-serving Czech 1-6, 6-4, 6-1, looked well out of his depth in surrendering the first set. But the match turned on its head midway through the second set, and the Russian won 11 of the last 13 games to dispatch the world number 20 in an hour and 48 minutes.
The 19-year-old, ranked 39, showed during the summer he has the potential to climb far higher, getting the better of world number nine Grigor Dimitrov and number 14 David Goffin at the U.S. Open.
Meanwhile world number one Rafa Nadal, who ended Rublev Flushing Meadows run in the quarter-finals, on Thursday pulled off a routine 6-3 6-3 victory over another young Russian, 21-year-old Karen Khachanov.
"I think I played a solid match," said Nadal, who looked more like his usual self after surviving a scare in the first round against Lucas Pouille, when the Frenchman held two match points.
Nadal next plays American John Isner who beat Leonardo Mayer 6-0, 6-3.
"Tomorrow will be a tough one against Isner; he's playing unbelievably well. I saw his match today. He played huge," the Spaniard said.
Alexander Zverev bested Italy's Fabio Fognini 6-4, 6-2 in the day's late match.
Raonic crashes out of Japan Open with new injury
Former world number three Milos Raonic pulled out of the Japan Open with a calf strain on Thursday, just two days after returning from a seven-week layoff that followed surgery on his left wrist.
Seeded third, the Canadian was forced to retire after one game of his second-round match against local hope Yuichi Sugita.
"I picked up a strain to the calf. It's hard to know the extent of it...," Raonic told the ATP World Tour website.
"It happened when the score was deuce, I felt a sharp pain at the back of my leg. I will head home now and get medical attention."
A three-time former finalist in Tokyo, Raonic beat Serbia's Viktor Troicki 6-3, 6-4 in Tuesday's first round.
The Canadian won the last of his eight career titles in Brisbane last year and has since dropped out of the top 10.
Nishikori in race to return for Australian Open
Kei Nishikori is entered to play in the Australian Open, but the jury is still out on whether the Japanese can recover from a season-ending wrist injury in time for the year's first grand slam, his manager said on Thursday.
The 27-year-old, who was ranked fourth in the world in March, pulled out of the Cincinnati Masters in August after tearing a tendon in his right wrist and has not played since.
Nishikori has dropped to 14th in the rankings after missing the U.S. Open, the final grand slam of the year, but is also entered to play in the Brisbane International, a warm-up for the year's first major in Melbourne.
"Kei's rehabilitation is on track and the medical team is satisfied with the current progress," his manager told Reuters in an email.
"Having said that, we will only get a clear picture as to the exact point of return to the tour once Kei is back on the court and practising at 100 percent capacity.
"The goal is to be practising at full capacity in December and be ready for Australia. We will learn more in the next month if this is feasible."
Nishikori's participation at February's New York Open on Long Island was confirmed by tournament organisers on Wednesday.
He is also registered to play at tournaments in Acapulco, Indian Wells and Miami in March next year.