Second seed Rublev was the latest scalp of Cerundolo's fine run of form, the Argentine making it seven consecutive wins by wrapping up a 6-4 6-2 success in just an hour and a half in Germany.
Having furthered his momentum with a second top-10 win in as many weeks, Cerundolo said: "It is the first time it has happened for me. I am playing against the top guys and I am playing well, it is unbelievable."
Cerundolo will face Aslan Karatsev in the last eight after he recovered from a set down to beat Daniel Elahi Galan 3-6 6-3 6-4.
World number six Alcaraz fared better than Rublev, registering a 7-6 (7-4) 6-3 win over Krajinovic to tee up a final-four meeting with Karen Khachanov, who beat Fabio Fognini in straight sets.
Meanwhile, a host of big names including Casper Rudd and Matteo Berrettini reached the last eight of the Swiss Open in Gstaad, as Dominic Thiem continued his revival with a win over Federico Delbonis.
Thiem reached his second quarter-final in as many weeks with an impressive 7-6 (8-6) 6-3 triumph despite letting a 5-2 lead slip in the opener, registering his first tour-level straight-sets victory since May 2021.
Having set up a meeting with Juan Pablo Varillas, the 2020 US Open champion beamed: "I have won two matches which means a lot to me right now, I really need those ranking points. Every match win is something very special."
The Austrian will be joined in the next round by first and second seeds Ruud and Berrettini, who eased past Jiri Lehecka and Richard Gasquet respectively.
Spanish duo Albert Ramos-Vinolas and Pedro Martinez also both progressed to the last eight despite dropping a set, with the latter setting up an enticing clash with Berrettini on Friday.
Rublev trailed Denis Shapovalov by a set but fought back to prevail 4-6 6-3 6-4 and ensure there will be a home hope in the final.
He saved five of six break points in the process of earning victory over the Canadian, the win moving Rublev ahead of Diego Schwartzman into eighth place in the battle to qualify for the season-ending tournament in London.
His opponent will be 2019 finalist Coric, who will be looking to go one better than last year after he staged a turnaround of his own.
Coric, beaten by Daniil Medvedev in his previous appearance in the final, saw off Milos Raonic 1-6 6-1 6-4.
Alexander Zverev progressed to his second final since the resumption of the ATP Tour at the Cologne Indoors.
Zverev overcame Alejandro Davidovich Fokina 7-5 7-6 (7-3) but was full of praise for the NextGen ATP Finals contender.
"He played much better tennis and I think he's somebody who is going to go up the [FedEx ATP] Rankings very quickly," Zverev said.
"For me he's a great guy as well. He's very talented, extremely good with the hands. I think he's somebody who's going to find his way up and it's going to be interesting to see what the future weeks [hold for him] this year and next year as well."
The German will meet Felix Auger-Aliassime, who recorded a 6-3 1-6 6-3 triumph over Roberto Bautista Agut.
At the Sardegna Open, Marco Cecchinato routed Danilo Petrovic 6-1 6-0 and will face Laslo Djere in the final after Lorenzo Musetti retired in the third set with a right elbow injury. Djere was leading 2-6 6-2 4-1.
The Russian had already prevailed in Belgrade, Dubai and Marseille this year and added another crown to his collection with a 6-2 6-3 victory against Korda in 75 minutes.
Top seed Rublev had dropped only one set in his three matches en route to the final and impressed against Korda with 29 winners, three breaks and just four unforced errors.
Korda, seeking a second Tour-level trophy following success in Parma last year, had his serve broken in the fourth and eighth games of the opening set.
Some heavy-hitting exchanges kept spectators gripped, though Rublev proved too strong for Korda in the second set and earned the only break in the sixth game.
Rublev got over the line with his fourth match point and remains sixth in the chase for an ATP Finals spot, with four of those ahead of him already qualified, along with Novak Djokovic.
Rublev – the world number five – won 6-2 6-1 over local 20-year-old Nakashima at the ATP 250 tournament on Wednesday.
Nakashima claimed only two of 18 second serve points for the match, with Rublev breaking him six times and triumphing in one hour, two minutes midweek.
The result improves 2021 Australian Open quarter-finalist Rublev's record to 45-15 this calendar year.
Rublev will take on sixth seed Diego Schwartzman, who rallied to defeat Lloyd Harris 4-6 6-3 6-2 in San Diego.
Fifth seed Hubert Hurkacz moved into the next round with a 7-6 (7-2) 6-1 victory over Australian qualifier Alex Bolt.
Hurkacz will face Russian and 2021 Australian Open semi-finalist Aslan Karatsev in the round of 16.
Daniel Evans – the eighth seed – overcame former Wimbledon and US Open runner-up Kevin Anderson 7-6 (13-11) 7-5 after more than two hours on court.
Evans will meet countryman Cam Norrie next.
Rublev won this tournament in 2020 and looked to be on his way to the final four after a strong opening set put him ahead.
But Lehecka battled back in the second to level the match and then found a crucial break in the second game of the deciding set to seize the advantage.
It was a lead he would not relinquish, holding his nerve despite watching a pair of match points come and go to clinch victory and knock out the world number five.
Lehecka will meet Murray in the semi-finals after the Brit came from a set down to see off Alexandre Muller 4-6 6-1 6-2 and keep his hopes of winning the Qatar Open for a third time alive after back-to-back titles in 2008 and 2009.
A tough opener had Murray facing a deficit against the world number 170, but a typically gutsy display saw him pull off the comeback and reach his first tour-level semi-final since June 2022, when he lost in the Stuttgart Open final to Matteo Berrettini.
Medvedev sealed his place in the final four with a hard-fought 6-2 4-6 7-5 win over Christopher O'Connell.
The world number eight triumphed for the seventh straight match, but did not have it all his own way against his Australian opponent, needing a crucial break with the final set tied at five games each to put himself back into the ascendancy.
Felix Auger-Aliassime awaits Medvedev in the next round after prevailing over Alejandro Davidovich Fokina in straight sets.
The world number nine out-aced his opponent eight to two to author a 6-4 7-6 (7-5) victory after one hour and 48 minutes, and he will look to improve on his dismal record against Medvedev on Friday, having lost all five of his meetings against the Russian.
At the Open 13 Provence, top seed Hubert Hurkacz reached the quarter-final after rallying from a set down to see off Leandro Riedi 4-6 6-3 6-2.
Second seed Jannik Sinner was forced to withdraw through illness, sending wildcard Frenchman Arthur Fils into the final eight, where he will meet Stan Wawrinka.
Alex De Minaur teed up a clash with Benjamin Bonzi by cruising past Alexander Ritschard 6-3 6-3, while world number 25 Grigor Dimitrov will play Alexander Bublik on Friday after beating Gijs Brouwer in straight sets.
Moutet, 20, beat Milos Raonic in the second round and on Friday overcame Fernando Verdasco and top seed Stan Wawrinka in three sets to reach his first final at this level.
However, getting the better of Rublev - the runner-up in 2018 - proved too much of a challenge, with the promising 22-year-old kicking off his season by claiming a third ATP Tour title of his career that will send him into the top 20 for the first time.
Rublev did not drop a single set throughout the tournament and after taking a 6-1 lead in the second-set tie-break against Moutet he did not look like missing out on the trophy.
"It's amazing. For the moment I have no words. I'm always really happy to play here and to win a title here is something special for me. It's an amazing start to the season and I can hope to continue the same level," Rublev said in his on-court interview.
"There's still much to work on, but I'm happy to become a top-20 player. I still have huge room to improve and I want to try to my maximum and see what happens."
The world number nine battled through an up-and-down opener before remaining patient to seal the second set and the match on Thiem's serve, taking a 6-4 6-4 victory.
Russian Rublev has now won eight successive sets of tennis against the 2020 US Open champion, and he is one win away from his fourth title of 2022 after triumphs in Belgrade, Dubai and Marseille.
Speaking on court after the win, Rublev said: "I was lucky I played a really good game and Dominic helped me out a little bit.
"Then I felt more confident and I was able to win in two sets, which was the most important thing. This week I have been playing really well, and I'll try to show my best tennis of the week tomorrow."
Korda will be Rublev's opponent on Sunday after the American saw off France's Arthur Rinderknech for a 7-6 (7-2) 6-3 win.
Meanwhile, at the Firenze Open, top seed Felix Auger-Aliassime saw off home favourite Lorenzo Musetti 6-2 6-3, moving one step closer to a second ATP Tour title.
The Canadian will face JJ Wolf in the final in Florence, after the American clinched a 6-4 6-4 win over Sweden's Mikael Ymer.
The Russian won 7-6 (7-5) 6-7 (7-9) 6-4 in a three-hour test, putting him one step away from a second title in 2020.
After triumphing at the Qatar Open last weekend, Rublev, 22, has brought his best form to Australia and had a marginal edge over his 19-year-old Canadian opponent.
At one point Rublev looked like getting the job done in straight sets, but teenager Auger-Aliassime dug deep to force a decider as he sensed the opportunity to grab a first ATP Tour title this weekend.
It went Rublev's way eventually as he advanced to a title match against South African Lloyd Harris, who had earlier beaten American Tommy Paul 6-4 6-7 (3-7) 6-3 in a battle between two qualifiers.
Harris and Paul, both aged 22 and ranked respectively 91st and 90th in the world, were unlikely semi-finalists, and Harris will go into the final as the obvious underdog.
The Auckland Open will crown its first French champion after Benoit Paire and Ugo Humbert won through to its final.
Dating back to the 1950s, the tournament crowned a host of the world's elite players in its early years, including Rod Laver, Roy Emerson and Bjorn Borg, and its list of winners reflects the cosmopolitan nature of the tour.
Yet French success has been in short supply, until now.
Humbert was a 7-6 (7-5) 6-4 winner against American John Isner, sending the 21-year-old left-hander through to his first tour final.
Paire fended off Poland's Hubert Hurkacz 6-4 6-7 (1-7) 6-2 and will target his fourth ATP title.
"I am very happy to play against a compatriot tomorrow," said 30-year-old Paire, quoted on the ATP website. "He is a very nice guy and we will see, but I am very happy to be in the final. It was the first time for me in the [Auckland] semi-finals and now the first time for me in the final."
Top seed Rublev won 6-1 7-5 in one hour and 52 minutes over the Argentine, who kept on coming throughout the contest.
The Russian world number five's victory books his spot in the last four where he will face Briton Cameron Norrie, who upset fourth seed Denis Shapovalov 6-3 6-1.
Rublev is featuring in his eighth semi-final of the calendar year and chasing his first title since winning in Rotterdam in February.
He had been a break up in the second set after dominating the first, but Schwartzman broke back.
The second set appeared destined for a tie-break with Schwartzman up 40-0 on serve at 5-6, before Rublev won the next five points to claim victory.
"The second set was very tough and enjoyable for the spectators to watch," Rublev said. "Every game was really tough with amazing points and the set could have gone either way."
Second seed Casper Ruud defeated Lorenzo Sonego 6-1 6-4 to book his semi-final spot where he will meet Grigor Dimitrov who beat Aslan Karatsev in three sets.
Ruud's win improved his 2021 record to 45-12, with the 22-year-old Norwegian rising to a ranking of 10.
Top seed Rublev won 6-1 7-5 in one hour and 52 minutes over the Argentine, who kept on coming throughout the contest.
The Russian world number five's victory books his spot in the last four where he will face Briton Cameron Norrie, who upset fourth seed Denis Shapovalov 6-3 6-1.
Rublev is featuring in his eighth semi-final of the calendar year and chasing his first title since winning in Rotterdam in February.
He had been a break up in the second set after dominating the first, but Schwartzman broke back.
The second set appeared destined for a tie-break with Schwartzman up 40-0 on serve at 5-6, before Rublev won the next five points to claim victory.
"The second set was very tough and enjoyable for the spectators to watch," Rublev said. "Every game was really tough with amazing points and the set could have gone either way."
Second seed Casper Ruud defeated Lorenzo Sonego 6-1 6-4 to book his semi-final spot where he will meet Grigor Dimitrov who beat Aslan Karatsev in three sets.
Ruud's win improved his 2021 record to 45-12, with the 22-year-old Norwegian rising to a ranking of 10.
Auger-Aliassime defeated Rublev in Rotterdam last week on the way to securing his maiden ATP Tour title, though all of their past meetings had required a deciding set.
Canadian Auger-Aliassime immediately broke Rublev, but the world number seven battled back to eventually claim the first set after a tense 56-minute opening exchange.
The pair twice exchanged breaks in the following set, with Rublev failing to serve out for the match at 5-4 before saving a set point at 5-6 down.
Rublev rallied from that point onwards, however, claiming his ninth tour-level triumph after a second set tie-break.
The Russian will look to become just the third man in the tournament's 30-year history to win the singles and doubles titles in the same edition when he takes to the court with Ukraine's Denys Molchanov in the doubles final.
A recent US Open quarter-finalist, world number 69 Van de Zandschlup claimed the first top-10 win of his career on Friday.
The 26-year-old also advanced to the semi-finals of an ATP event for the first time.
There, he will face 2011 champion Marin Cilic, who was a 6-4 3-6 6-3 winner over third seed Roberto Bautista Agut.
Denis Shapovalov was another big-name casualty in Russia, the second seed going down 4-6 3-6 against world number 53 Jan-Lennard Struff.
Although, there were better fortunes for fifth seed Taylor Fritz. The Indian Wells semi-finalist is yet to drop a set this week after prevailing 6-4 6-2 against John Millman.
Elsewhere, Matteo Berrettini was the victim of another upset at the Erste Bank Open in Vienna.
The Wimbledon champion went down 1-6 7-6 (7-2) 6-7 (5-7) following a two-hour 40-minute battle with Carlos Alcaraz.
Reaching his first ATP 500 semi-final, the Spanish teenager claimed another big scalp having defeated Stefanos Tsitsipas at Flushing Meadows last month.
However, second seed Alexander Zverev remained on course for a fifth title of the season, as he claimed his 300th tour-level win.
The Australian Open finalist beat Felix Auger-Aliassime 6-4 3-6 6-3, avenging his fourth-round defeat by the Canadian at Wimbledon in July.
Mannarino ultimately came out on top 5-7 7-6 (7-4) 6-3 but he had to do it the hard way, coming back from match point down to set up a meeting with Ricardas Berankis, who lost only tree games in a 6-2 6-1 win over Federico Coria.
Rublev was never cruising, however, as Mannarino only just fell short in the first set and then took the second to a tiebreak, which he eventually won to turn the tide.
The 33-year-old, who lost to Rublev in the final two years ago, took things up a notch in the decider and did not face a single break point as he got the job done despite the home support.
"The crowd was cheering for Andrey but that is normal," he said after reaching the quarter-finals. "I was happy to play with such a nice atmosphere.
"We have been playing for a long time without fans, so it is nice to enjoy a stadium with crowds now."
Second-seed Aslan Karatsev is now the favourite in Moscow, and the Russian had few issues in a 6-4 6-3 defeat of Egor Gerasimov.
Karatsev will face Gilles Simon next following his 6-3 6-2 win over Mackenzie McDonald, while Pedro Martinez won 6-3 6-4 over Filip Krajinovic to book his passage.
At the European Open in Antwerp, Andy Murray's hopes of winning a first ATP Tour title in two years were ended by number two seed Diego Schwartzman.
The Argentinian trailed 4-1 in the first set but fought back to win 6-4 7-6 (8-6) in his first ever match against the Scot, whose last tour triumph was in Antwerp.
In his on-court interview, Schwartzman said: "It was a pleasure to play against Andy. We had not played before and he is coming back and every week he is playing better and moving better.
"I have a lot of respect because when I grew up playing tennis, I was watching Roger [Federer], Rafa [Nadal], Andy and Novak [Djokovic] and right now playing against him is a pleasure for me."
Seventh seed Lloyd Harris is also into the quarter-finals after a straightforward 6-2 6-3 victory over Jan-Lennard Struff in just 72 minutes, Marton Fucsovics came through 6-7 (5-7) 6-3 6-1 against Roberto Bautista Agut and Brandon Nakashima edged past Henri Laaksonen 7-6 (7-5) 6-7 (5-7) 6-3 to earn the right to face Schwartzman.
Appearing as the top seed at an ATP event for the first time, Rune had lost both his previous meetings with Huesler, including last season's Sofia Open.
However, the world number nine made it third time lucky to set up a last-eight clash with Gregoire Barrere, who beat Nikoloz Basilashvili in straight sets.
Meanwhile, third seed Borna Coric is now just one win away from securing a return to the top 20 in the ATP rankings. The world number 23 – and reigning Cincinnati champion –saw off Arthur Rinderknech 6-3 7-5.
Although, there was no joy for Alejandro Davidovich Fokina. The fifth seed was ousted 6-3 6-3 by world number 70 Quentin Halys, who claimed only his second top-50 career win in 20 attempts.
Seventh seed Emil Ruusuvuori was also eliminated in straight sets by Maxime Cressy, but Lorenzo Sonego overcame Filip Krajinovic to book a quarter-final date with Jannik Sinner.
Still just 19, Rune added to his maiden crown in Munich five months ago with a 6-4 6-4 triumph over world number five Tsitsipas in a match lasting 95 minutes.
Tsitsipas, who was seeking a 10th ATP title and a third this season, had not dropped a set in his previous three matches en route to the final.
However, he was broken in the third game of both sets against Rune, who is the second teenager after Carlos Alcaraz to win multiple ATP titles in 2022.
Rune fired 20 winners and saved the only break point he faced – that coming in the sixth game of the second set – on his way to becoming the first Danish champion in this event.
"It was an unbelievable match from my side," Rune said in his on-court interview. "I knew it was going to be difficult, but I just tried to stick to the game plan.
"I had to play my best tennis today, and it was good that I could find the level. I am super happy. It was very close to perfection.
"I was making a lot of returns and playing pretty well behind my serve. Stefanos is an amazing player, who always makes it difficult. It was a super fun match to play."
Both men were playing in their maiden tour-level final on debut at the ATP 250 event in Munich, and Rune becomes the third-youngest Munich champion in the Open Era.
Eighth-seed Van de Zandschulp was leading 4-3 in the first set, with his Danish opponent serving at 40-15 when the Dutchman retired due to an aching chest.
"This was probably the worst way to win a final,” Rune said. "I was obviously expecting a very tough match and he came out very strong.
"I just wish him all the best, a speedy recovery, and we all just hope to see him back on the court very soon."
Rune, who turned 19 on Friday, had a memorable week in Germany, including securing his first victory against a top 10 opponent when he beat world number three Alexander Zverev in the second round, before also getting past Jiri Lehecka, Emil Ruusuvuori and Oscar Otte on his way to the final.
"I'm super happy, of course," Rune continued. "As I said, not the way I want it to end, but if I look through the week, what a week.
"I played some unbelievable tennis, really fighting my way through it. To be playing here in Munich and winning my first ATP title in front of such a brilliant crowd, I couldn't really ask for more."
Ruud, a French Open finalist and defending champion in Bastad , lacked his usual composure as world number 39 Cerundolo broke him three times to win 6-4 3-6 7-5 on Wednesday.
That marked a first top-10 career victory for Cerundolo after defeating world number five Ruud, guiding him to his first quarter-final appearance at the tournament.
"I'm feeling amazing, I'm really happy," said Cerundolo, whose previous best result was beating world number 24 Gael Monfils. "It's amazing getting my first Top 10 win. It's been the best year so far in my career.
"He's a French Open finalist and was the defending champion here, so it was a big challenge for me and I'm happy to go through."
Aslan Karatsev awaits in the quarter-finals Cerundolo after downing Frenchman Hugo Gaston 6-2 6-4.
Fifth seed Pablo Carreno Busta survived a first-set scare to defeat 2016 champion Albert Ramos-Vinolas 4-6 7-6 (7-5) 7-5.
The victory was Carreno Busta's 250th tour-level triumph and he will next face third favourite Diego Schwartzman, who overcame Elias Ymer in straight sets.
Third seed Alexander Bublik was made to work for a 6-3 3-6 6-2 second-round victory over Jack Sock in Newport and Andy Murray edged past Wimbledon doubles champion Max Purcell.
Murray needed almost two-and-a-half hours to get the better of Purcell, eventually triumphing 4-6 6-2 6-1 to tee up a last-eight meeting with Bublik.
Fourth favourite Maxime Cressy had little trouble in beating fellow American Mitchell Krueger 6-3 6-4 and will next face Steve Johnson, who progressed past seventh seed Jiri Vesely with a walkover.
Benjamin Bonzi, ranked as fifth seed in the United States, eased past Christopher Eubanks in straight sets, while James Duckworth triumphed 7-5 3-6 6-2 over Quentin Halys.
John Isner joined the list of favourites who made the third round in routine fashion, beating Peter Gojowczyk in straight sets 6-3 7-6 (8-6), before top seed Felix Auger-Aliassime faced some adversity against Jason Kubler following the Australian's strong run into the fourth round of Wimbledon.
Auger-Aliassime has a slight advantage, leading 6-4 3-6 6-5 before play was suspended due to poor light. When play resumes, Kubler will serve with a chance to force a third-set tiebreak.
The 22-year-old Norwegian has rocketed from outside the top 50 to 16th currently in the world rankings in just 18 months, and he is the top seed this week in Sweden.
Such a status is all rather novel for Ruud, but he breezed to a 6-0 6-2 win over 18-year-old Danish wildcard Holger Vitus Nodskov Rune on Thursday.
That carried him through to a quarter-final meeting with Swiss player Henri Laaksonen.
Ruud is back on clay this week, having enjoyed great success on the surface already this season, reaching semi-finals of the Masters 1000 events in Madrid and Monte Carlo, while also winning a title in Geneva.
A first-round exit on the Wimbledon grass followed those positive results, so another event on clay comes as a boost.
"It is a surface I have had the most success of my career, it is great to be back here in Bastad," Ruud said after crushing Rune's hopes.
"There is a bit of extra pressure [being the top seed]. In a match like this against a fellow Scandinavian younger player, it is even more."
He added, quoted by the ATP website: "I think I was very professional in my mindset today. I played a match without any errors really from the first to the last point.
"It is a nice feeling being the top seed but also pressure. I felt great crowd support, it is nice to feel that energy."
Qualifier Laaksonen beat Elias Ymer 6-2 7-5, while third seed Fabio Fognini was bounced out of the tournament, losing 6-3 1-6 6-4 to Spain's world number 97 Roberto Carballes Baena, who will tackle Slovakian Gombos in the last-eight stage on Friday.
At the Hamburg European Open, Pablo Carreno Busta justified his standing as second seed with a 7-5 6-3 win over fellow Spaniard Carlos Taberner to reach the quarter-finals.
Stefanos Tsitsipas is the top seed this week at the tournament in Germany and won through to the last eight on Wednesday.
Others to move through the rounds in Hamburg on Thursday included Dusan Lajovic and Federico Delbonis, the latter advancing with a handy 6-3 7-6 (7-4) win over fourth seed Albert Ramos-Vinolas.
Ruud had to dig deep in the deciding set, breaking Sousa when the Portuguese was serving for the title at 5-4, before going on to win 7-6 (7-3) 4-6 7-6 (7-1).
The world number nine has now won six of his last seven ATP 250 events on clay, and is the first player since Stan Wawrinka (2016 and 2017) to win more than one Geneva Open title.
Ruud served five aces in the first set on his way to edging a tie-break, but a determined Sousa was able to level in a second set in which he won eight of 11 second-service points.
It looked like Sousa would cause an upset against the tournament's second seed when serving for the match, only for Ruud to break back and use that momentum to take the win.
The Norwegian made the semi-finals at the Internazionali d'Italia last week and maintained his momentum ahead of the French Open by lifting the trophy in Switzerland.
"It was one of the craziest matches that I have ever played," he said in his on-court interview. "It was a lot of up and down. Sousa was close to winning and then suddenly everything turns around and this is tennis.
"This win feels so good, but you have to give a lot of credit to Joao because he fought back from one set down and has been playing well all week.
"It was just a matter of one or two points today and luckily they went in my favour."
At the Lyon Open, it was Cameron Norrie who emerged triumphant as the Brit beat Alex Molcan 6-3 6-7 (3-7) 6-1.
Norrie – who was beaten by Stefanos Tsitsipas in last year's final – was largely on top throughout, firing down six aces and boasting an impressive success rate of 72 per cent of first serve points won, while also saving five of seven break points against his Slovakian opponent.
The top seed could have won in straight sets, but was unable to convert two match points in the second before being forced to a decider by Molcan.
It is Norrie's second ATP title of the season and the fourth of his career. It is his first on clay as he prepares for the second grand slam of the year at Roland Garros.
"It is my first title on the clay so it means a lot to me," Norrie said. "I can't be happier with how I handled everything this week. This one feels the best so far. I don't know why, it is just so special and I couldn't be happier and am really speechless right now. It was an incredible atmosphere. Thanks to everyone for coming out.
"I had chances to close the matches in straight sets this week and get it done easier than usual and it didn't go that way and I was able to let that go and respond. In the third set I moved really well and it is nice to get over the line."
The top seed was given a second set scare by the Chilean but wrestled back control to emerge as the victor in a 6-2 3-6 6-3 encounter.
The two-time grand slam finalist, having been runner-up at Wimbledon and the US Open this year, will face Yoshihito Nishioka after he saw off Japanese compatriot Taro Daniel in a 6-2 6-4 win.
His victory also ensured his place at the ATP Tour's end-of-year finale in Turin, alongside Spanish duo Rafael Nadal and Carlos Alcaraz.
Cameron Norrie remains on course to set up a potential final in Korea with Ruud after brushing aside Kaichi Uchida with a comfortable 6-2 6-2 victory.
The Briton will face eighth seed Jenson Brooksby after he turned over home favourite Kwon Soon-woo in a 6-3 6-4 result in Seoul.
Brooksby's fellow Americans Mackenzie McDonald and Aleksandar Kovacevic also came through their last-16 encounters to set up a quarter-final clash against each other.