Nishioka was the highest seed in action on the first day of the tournament, and he had his back up against the wall after failing to win a game in a troubling second set, but produced three breaks of serve in the back-and-forth decider.
Meanwhile, Ecuador's Emilio Gomez earned a shot at top seed and world number seven Taylor Fritz after advancing 7-6 (7-3) 6-4 against Taiwan's Tung-lin Wu.
Portugal's Nuno Borges continued his winning run after earning his spot through the qualifiers, eliminating America's Steve Johnson 6-4 3-6 6-4, but the crowd got something to cheer for when the USA's Denis Kudla got the better of Australia's Jordan Thompson 3-6 6-4 7-6 (7-2).
Further south at Argentina's Buenos Aires Open, Serbia's Laslo Djere booked a blockbuster showdown against world number two Carlos Alcaraz after repelling the challenge of Italy's Fabio Fognini 6-4 6-4.
Argentinian Pedro Cachin put on a show for his hometown fans with a 7-6 (7-2) 6-4 victory over Brazil's Thiago Monteiro, but Cachin's compatriot Guido Pella had less success with a 6-4 7-5 defeat at the hand of Spain's Jaume Munar.
Nishioka moved into the second round in Seoul with a 6-2 7-6 (7-3) defeat of the Briton.
The world number 56 from Japan will face Taro Daniel or Emilio Gomez in round two after winning 70 per cent of points on his first serve and breaking Evans four times.
Jenson Brooksby was forced to go the distance, but delivered a final-set bagel as the eighth seed saw off Wu Tung-lin 7-6 (7-5) 3-6 6-0.
Qualifier Nicolas Jarry will take on top seed Casper Ruud after defeating Ryan Peniston 6-3 7-6 (10-8), while American duo Mackenzie McDonald and Steve Johnson also advanced.
Tseng Chun-hsin progressed with Chris O'Connell retired with an injury after losing the first set before Kwon Soon-woo beat Yunseong Chung in an all-South Korean contest.
Norrie eventually overcame the American fifth-seed after a final set tie-break, winning 6-2 1-6 7-6 (7-4).
The Brit's tenacity was key, saving seven of 10 break points, and he will now face another American, Tommy Paul, in the final four in Florida after he beat qualifier Stefan Kozlov 6-3 6-1.
The other semi-final will be contested between Reilly Opelka and John Millman after they bested Adrian Mannarino and Grigor Dimitrov respectively.
Opelka was taken to a third set by his French opponent before winning 7-6 (7-2) 3-6 6-1, hitting 19 aces on his way to victory.
Millan proved too good for third seed Dimitrov winning 6-4 6-4 in an hour and 34 minutes where the Australian's return was a highlight.
At the Rio Open, rain washed out many of the scheduled matches on Friday, with Diego Schwartzman against Pablo Andujar and Miomir Kecmanovic against Francisco Cerundolo both cancelled.
Matteo Berrettini and Thiago Monteiro were finally able to finish their round of 16 match at 11.35pm local time, with the Italian securing victory 6-4 6-7 (6-8) 6-3.
He will play seventh seed Carlos Alcaraz who overcame Federico Delbonis 6-4 7-6 (7-1) after their match was pushed back, starting not long prior to midnight local time.
British top seed Norrie triumphed 6-2 6-2 in one hour and 23 minutes as he marks another milestone in his career-best season.
Norrie, 25, now has the most wins on the ATP tour this year, going past world number one Novak Djokovic with 35.
The 19-year-old American could not handle Norrie's first serve, while the Briton converted five of his eight break points.
Norrie served for the match with Nakashima pressing him in a tight final game but the top seed rounded out a breakthrough win.
Norrie won 21 of 29 points on his first serve, going at 72 per cent, with Nakashima breaking him once.
There was an upset at the ATP 250 tournament, where Russian star Rublev fell to Norrie 3-6 6-3 6-4 in San Diego on Saturday.
Norrie clinched his third career top-10 win as the Brit looks to secure his second ATP Tour-level title on Sunday.
"It's nice to get some revenge. He beat me easily last time, so it's good to see I've improved a little bit," said Norrie, who lost to Rublev in St Petersburg last year.
Standing in Norrie's way is second seed Ruud, who saw off former world number three Dimitrov 6-4 4-6 6-4.
Norway's Ruud – ranked 10th in the world – has the chance to win his fifth title of the season, the most of any player on the ATP circuit.
Norrie holds a 41-19 win-loss record in 2021 and the 26-year-old added ahead of Sunday's decider: "I'm just trying to enjoy today and then I'll try to rest up and get ready for [the final].
"I've been watching both of them this week and they've been playing some of their top level. I'm looking forward to that one tomorrow."
In a battle between two of the United States' brightest young men's tennis talents, neither could find a way to break the other's serve.
That meant it came down to the shoot-out of the tie-break in each set, with Opelka sealing a 7-6 (7-5) 7-6 (7-3) victory in an hour and 51 minutes.
It gives the world number 23 a third ATP title of his career, all of which have been won in America. His previous successes came at Delray Beach and the New York Open.
This indoor showpiece on Sunday was just a second main-tour final for 54th-ranked Brooksby, a player who caught the eye in a breakout 2021 campaign, and he found Opelka's serve impenetrable, as has been the case for all-comers throughout the week.
Opelka faced just one break point in the title match, the first against his serve all week, but staved that off. He had five chances against the Brooksby serve but could also not take advantage.
Rather than power, Opelka finished off the match with finesse, hitting a backhand winner after a teasing exchange. He then described 21-year-old Brooksby as "a future top-10 player" after keeping the youngster waiting for his first ATP title.
Brooksby was ranked outside the top 300 this time last year and is poised for a first top-50 breakthrough.
The champion was delighted with his own game, with Opelka saying at the trophy presentation: "I thought I played very well under pressure, especially against a great player like Jenson.
"He makes you very uncomfortable and he took me out of my comfort zone a lot of the match today. I really had to play my best tennis to get by and I barely did."
With Saturday's play affected by rain, the big-serving American had only hours to prepare for the final after an impressive defeat of Raonic in 127 hard-hitting minutes.
Opelka edged the ace count 19 to 16 and also saved a match point against the Canadian in their semi-final, eventually coming out on top 4-6 7-6 (8-6) 6-3.
The world number 54 broke Raonic for the first time at 3-3 in the final set and then again to love to book his place in the final, where he showed no signs of tiredness when seizing the initiative by claiming the third of three set points to forge ahead against Nishioka.
However, Nishioka's return game began to click into gear and he levelled the match when Opelka sent a forehand long to lose a tense tie-break.
An immediate break put Opelka in charge of the decider, though, and he moved 5-2 up when a furious Nishioka sent a backhand wide having previously saved three break points.
Opelka secured his second ATP Tour title with a 27th ace, once again prevailing in a three-set tussle.
Number six seed Paire was a 6-3 7-6 (7-2) winner in his first-round match against Jozef Kovalik.
The Frenchman was not broken in the match, saving all eight of the break-point opportunities he offered up to Kovalik during a competitive 85-minute contest.
Paire's win follows a quarter-final appearance at the Hamburg European Open last week as the 32-year-old begins to recover from a dreadful first half of 2021.
Prior to his run in Hamburg, Paire had only won two ATP Tour matches this year.
Mikael Ymer had to come from behind before he progressed with a 4-6 6-3 6-3 win over lucky loser Enzo Couacaud.
The top four seeds at the ATP 250 event – led by Wimbledon semi-finalist Denis Shapovalov – get a bye through the first round and are therefore yet to begin their campaigns.
At the Croatia Open Umag, meanwhile, Radu Albot came out on top as he claimed a three-set victory over Holger Rune, with top seed Albert Ramos-Vinolas and defending champion Dusan Lajovic not in action on day one.
Paire was drawn against compatriot Gregoire Barrere in a battle of two home hopefuls, but the more established player triumphed in straight sets.
The 20th-ranked star broke in the third game of the opener and protected his advantage in straightforward fashion.
There were no breaks in the second, but Paire dominated the tie-break to claim a 6-4 7-6 (7-1) victory.
Barrere was not the only Frenchman to exit the competition, as former world number seven Richard Gasquet went down 6-3 3-6 7-5 to Mikael Ymer.
Ymer will now meet Stefanos Tsitsipas, the defending champion and number two seed, who was granted a first-round bye.
In the final match of the day, Alexander Bublik defeated Marton Fucsovics 6-4 7-5.
The Frenchman - ranked no. 49 in the world - marked his debut at the ATP 250 event by ending a three-match losing run, progressing after one hour and 37 minutes on court.
Paire, who recorded five breaks of serve en route to victory, will be up against either James Duckworth or Emil Ruusuvuori next.
"[I am] happy about the win," Paire said in his on-court interview. "It was not easy. Alejandro is a very good player, so I had to be focused on my game.
"I had to serve well and do my best and that is what I did and I am very happy and proud of my game today.
"I played well in the first game, it was good for my confidence. The most important thing is to stay on my game and stay focused. I was solid today so I am very happy."
Also in Monday's action, Adrian Mannarino was another seed to suffer an early exit, going down in straight sets to Gianluca Mager.
Miomir Kecmanovic came through a tight two-set contest to knock out Adrian Andreev, including taking the opener via a tie-break.
Paul edged the third seed 6-3 6-7 (2-7) 7-6 (7-2) in three hours and 29 minutes in their semi-final clash in Acapulco.
World number 23 Paul actually generated a match point late in the second set but spurned his initial chance, then waiting another two hours before winning in the third-set tie-break.
Paul let match point slip at 5-4 in the second set and had to rally back from 3-1 down in the third, but triumphed on his fourth match point.
"I couldn't be happier," Paul said. "The goal for this year was to get the ranking up and get more trophies. I only have one trophy on Tour between singles and doubles.
"You don't get trophies unless your in the final, and hopefully I can play another good match tomorrow and get the winner's trophy."
The 2023 Australian Open semi-finalist will take on Alex de Minaur in Saturday's decider, after he defeated Holger Rune 3-6 7-5 6-2 in two hours and 50 minutes.
In the Chile Open, local Nicolas Jarry progressed into the semi-finals with a 3-6 6-3 6-4 win over German qualifier Yannick Hanfmann. Jarry will face Spaniard Jaume Munar after he won 6-3 3-6 6-2 over Thiago Monteiro.
Third seed Sebastian Baez got past Laslo Djere 7-6 (7-4) 6-4, setting up a semi-final date with Tomas Martin Etcheverry after he won 6-1 6-2 over Dusan Lajovic.
It was the third day in a row that has been washed out due to persistent rain, but after completing their first set on Wednesday, and their second set on Thursday, Max Purcell was allowed to finish off his 6-4 3-6 6-3 win over Daniel Altmaier.
It was the final first-round matchup yet to conclude, although there is still a second round, quarter-finals, semi-finals and the final to schedule in limited time before the ATP Tour rolls on.
The tournament's top seed, Frances Tiafoe, is yet to play a match yet after receiving a first-round bye, and it is the same case for second seed Tommy Paul.
In a statement, tournament director Bronwyn Greer said: "We want to ensure that our courts are in the best possible condition to complete our tournament this weekend, and with that in mind we have decided to forgo play today with the exception of that first-round match that is deep into the third set."
Having lost to Shapovalov at the Auckland Classic last month, Pospisil will face him again following a 6-3 6-4 win over Bedene in the first round of the ATP 250 event on Monday.
Shapovalov, seeded third, has a bye in the first round along with Gael Monfils, David Goffin and Grigor Dimitrov.
Fifth seed Felix Auger-Aliassime does not play his opener until Tuesday, meaning the highest ranked player in action was Spain's Pablo Carreno Busta, but the Spaniard fell to a shock 3-6 6-4 6-3 defeat against Norbert Gombos.
In the day's other game, home favourite Gregoire Barrere sealed a round-two meeting with Dimitrov after a 6-2 7-6 (8-6) triumph over Joao Sousa.
At the Pune Open, fifth seed Yuichi Sugita cruised past Thomas Fabbiano 6-3 6-0, but there were defeats for home hopes Sumit Nagal and Ramkumar Ramanathan respectively in their matches against Viktor Troicki and Salvatore Caruso.
Ivo Karlovic is also out after losing in straight sets to Cedrik-Marcel Stebe, who will next face second seed Ricardas Berankis.
It is the second day in a row without a match being completed after Wednesday's play only made it through one set.
Max Purcell took the first set of his match against Daniel Altmaier on Wednesday, before Altmaier came back to win the second set on Thursday, and they will hope to complete the match on Friday when they resume with Purcell leading 6-4 3-6 4-3.
John Isner will likely have a do-or-die tie-breaker as soon as his match with Gijs Brouwer resumes, as he trails 6-4 5-6 with the Dutch competitor on serve.
The only other match underway is locked at 4-4 between Denis Kudla and J.J. Wolf.
The world number 14 continued his blistering form having also landed the Swedish Open and Swiss Open earlier this month.
The Norwegian has now won each of his last 11 matches since defeat by Jordan Thompson in the opening round at Wimbledon.
Ruud – also a winner at the Geneva Open in May – dominated the opening set against world number 97 Martinez, who was appearing in his first ATP final.
The Spaniard defeated second seed Roberto Bautista Agut on the way to reaching the showpiece, and responded well by taking a close second set.
Nevertheless, Ruud broke to take control of the decider, before closing out victory for a fourth ATP title of the season – all of which have come on clay.
The former world number one saved two match points in the first round match and eventually triumphed 7-6 (7-2) 6-7 (7-9) 7-6 (10-8) in three hours and 45 minutes.
Murray's victory in an epic clash was the longest three-set match of the 2021 ATP season.
The battle had so many twists and turns that Murray, a veteran of 897 matches on tour, ended up having a long debrief with Tiafoe in the locker room afterwards.
Murray revealed it was the first conversation of that nature he had been involved in for more than a decade.
Indeed, the Briton only remembered going back over a match with one of his opponents twice before.
"I spent probably 30 minutes in the locker room afterwards just chatting to Frances," Murray said. "I had a long chat with Frances afterwards so I'll probably remember that and then the embrace at the end.
"I guess so much went into it that I don't remember loads of points in the match, but obviously the end was special.
"I've never played a match like that on the tour really. In the locker room we had a much more in-depth chat about tennis - that was kind of rare I would say.
"I think maybe twice I've had that conversation in the locker room.
"Once was with [Jurgen] Melzer at the US Open after I beat him in five sets [in 2008] and we chatted a bit about the match.
"And then once after playing Jarkko Nieminen [at Wimbledon in 2010] because we were waiting to speak to the Queen after we played."
Murray faces a tough test in the last 16 as he is due to do battle with second seed Diego Schwartzman.
He hit 21 aces against Tiafoe and totalled 46 winners to just 21 unforced errors, but Tiafoe was also in form with 51 winners to 25 unforced errors.
"The margins were so fine," added Murray. "I served particularly well at the end, which helped, and when he missed his first serve on that match point I was able to capitalise on that.
"There's obviously so much that goes into a match like that."
Schwartzman will go into the next match fresher than Murray as the Argentine received a first-round bye due to his seeding.
Eighth seed Goffin, ranked at world number 52, prevailed 2-6 7-5 6-1 in Montpellier against the Frenchman.
It looked bleak for Goffin when Bonzi raced into a 3-0 lead in the second set, yet the Belgian reeled off three successive games to get himself back in the fight before snatching a crucial break to make it 6-5, and he did not look back from there.
"During the match I stayed positive even though I was one set and one break down," Goffin said.
"I tried to stay focussed, to stay as long as possible on the court to try to get some confidence, to work on certain things: to be more aggressive, [hit] a better quality of ball.
"At the end it was better and better, so I'm really happy the way I played at the end of the second and in the third."
Next up for Goffin is a tie with Spain's Alejandro Davidovich Fokina, or another Frenchman in the form of Adrian Mannarino, who lost to eventual Australian Open winner Rafael Nadal in Melbourne last month.
Monday's other match saw sixth seed Alexander Bublik defeat Tallon Griekspoor 7-6 (7-4) 7-6 (7-5).
Yuki Bhambri was the story at the Tata Open Maharashtra, as the Indian claimed a first tour-level match win in almost four years, beating Jozef Kovalik 6-7 (10-12) 6-2 7-5.
Bhambri, ranked at 863 in the world, had only played two singles matches on the ATP Tour since 2019 due to a knee injury and had last beat Mirza Basic in Miami in 2018.
"It is a privilege to play at home and it is an important win as well playing at my home tournament," he said. "Each match is tough at tour-level so I am just taking it one match at a time."
Radu Albot beat Federico Gaio in straight sets, while seventh seed Ricardas Berankis was shocked by Quentin Halys and Daniel Altmaier also progressed.
The world number eight triumphed in Switzerland 12 months ago with victory over Denis Shapovalov in the final, claiming the first of five ATP titles he won during an impressive campaign.
Fresh from reaching the semi-finals in Rome, the Norwegian – also a winner in Buenos Aires and a Miami runner-up this season – made a dominant start.
Although he was broken in game three of the opening set, Ruud responded immediately and a further four breaks wrapped up a commanding 6-3 6-1 victory in just 55 minutes.
Meanwhile, Reilly Opelka registered his first win on European clay this season as he saw off Christopher O'Connell.
Despite triumphing in Dallas and Houston earlier this year, Opelka has suffered first-round exits in Munich, Madrid and Rome since the latter.
Nevertheless, the fourth seed was in fine form in Geneva, hitting 13 aces on the way to defeating the Australian qualifier.
However, there was no joy for 2021 runner-up Shapovalov as the third seed crashed out 6-4 6-7(2) 6-3 to Ilya Ivashka.
Fifth seed Nikoloz Basilashvili fell 6-4 6-3 at the hands of 2015 finalist Joao Sousa, who progresses beyond round two for the first time since reaching the Championship match seven years ago.
There were more surprise defeats in Lyon, where second seed Pablo Carreno Busta was beaten 7-5 6-3 by Federico Coria.
After taking a close opening set, the world number 59 rallied from 3-1 down in the second to reach his fourth quarter-final of the season on clay.
Karen Khachanov also bowed out to Marrakech runner-up Alex Molcan 6-2 7-6(4), while Munich champion Holger Rune built on his momentum with a 6-4 6-3 victory over Adrian Mannarino.
Rain wreaked havoc in Rio, where only two quarter-final matches were completed at the ATP 500 tournament on Friday.
Thiem's back is against the wall, with the Australian Open runner-up and world number four down 7-6 (7-5) 2-1 against Mager – who is featuring in his first ATP Tour quarter-final.
Lucky loser Attila Balazs and qualifier Pedro Martinez were also playing when the rain returned in Brazil, with the latter leading 6-2 2-2.
Cristian Garin managed to win through to the semi-finals after the third seed claimed his seventh successive victory by rallying past Federico Coria 2-6 6-3 7-5.
Next up for Garin is fifth seed Borna Coric, who defeated Lorenzo Sonego 7-6 (7-5) 6-3 on the Brazilian clay.
At the Delray Beach Open, second seed Milos Raonic and fellow big server Reilly Opelka will meet in the semi-finals.
Raonic beat Steve Johnson 7-6 (8-6) 6-3 and 2019 New York Open champion Opelka took down Kwon Soon-woo 6-3 6-4 at the ATP 250 event.
"It's going to be tough. He gets a lot of free points on his serve and you've got to make him play," Raonic said.
"You can't just make him play though because he goes for it from the centre of the court. You've got to move in, you've got to find a way to be aggressive."
Elsewhere, Yoshihito Nishioka overcame teenager Brandon Nakashima 3-6 7-6 (7-5) 6-4 and sixth seed Ugo Humbert eased past 2018 winner Frances Tiafoe 6-1 6-2.
The 20-year-old American, who took a set off Novak Djokovic and rattled the world number one at the US Open, is shaping up as potentially his country's biggest hope for the future in the men's game.
Californian Brooksby crushed Spain's world number 44 Alejandro Davidovich Fokina 7-5 6-0, and second seed Schwartzman awaits after the Argentinian took down another 20-year-old American, Brandon Nakashima, scoring a 6-4 6-2 quarter-final win.
Schwartzman is the man who ended Andy Murray's hopes at the tournament in Antwerp.
Brooksby, who had to win two qualifying matches to reach the main draw, said: "Tomorrow will be a great match. I'm really looking forward to it. I'll get some rest tonight and get ready to battle again tomorrow."
The other semi-final will see Italian top seed Jannik Sinner take on South African seventh seed Lloyd Harris following their respective straight-sets wins over Arthur Rinderknech and Marton Fucsovics.
There will be an all-Russian semi-final at the Kremlin Cup in Moscow, after Aslan Karatsev and Karen Khachanov won through to the final four.
Second seed Karatsev sank the hopes of Frenchman Gilles Simon, breaking serve five times on the way to a 6-4 6-3 win, while third-seeded Khachanov edged out Australian John Millman. A 7-5 7-6 (7-4) grind featured 19 aces by Khachanov, the 2018 Kremlin Cup champion, who saved four set points in the second set.
Marin Cilic thrashed Pedro Martinez 6-1 6-2 to set up a tussle with Ricardas Berankis, the Lithuanian ending Adrian Mannarino's run with a 6-2 7-6 (7-1) success. Frenchman Mannarino had stunned Russian top seed Andrey Rublev in the previous round.
