Garcia defeated Swiatek in three sets on Friday, ending the world number one's 18-match winning streak on clay.
Paolini should have provided a far more straightforward task, and so it proved, as Garcia raced through 6-1 6-2 to make the title match.
The fifth seed will now face first-time WTA Tour finalist Ana Bogdan – a 7-5 7-5 victor against Kateryna Baindl – in that Warsaw decider.
Garcia will hope for better conditions for the showpiece, with rain having added another factor on Saturday, when the in-form French star was still recovering from stopping Swiatek.
"It's been a challenging week, especially today, with the big win yesterday, only a couple of hours to recover and be ready," Garcia explained.
"Conditions were very difficult, a lot of rain. I'm just very happy with the way I played, and I stayed very focused on the present, and it paid off."
At the Prague Open, Anastasia Potapova will face Marie Bouzkova in the final, the seventh seed playing the eighth seed.
Potapova had it largely her own way against Wang Qiang, who succumbed to a second-set bagel in going down 6-3 6-0, while Bouzkova also won in two but needed a tie-break in the opener against Linda Noskova, progressing 7-6 (7-4) 6-3.
Potapova faces a busy Sunday, as she had already advanced to the doubles final alongside partner Yana Sizikova.
The 29-year-old became just the second Frenchwoman after Amelie Mauresmo in 2005 to win the season-ending tournament by coming through a bruising encounter 7-6 (7-4) 6-4 in Fort Worth, Texas.
Victory propels Garcia back to a joint-career high ranking of fourth, having been languishing down in the mid-70s as recently as June following a series of injuries.
"It's definitely a lot of giant happiness," Garcia said at her post-match press conference.
"A crazy final, a lot of intensity on every point. Just really proud of the work we did through all the year. It was a great match – really went for it. I'm really happy to win my biggest title.
"Just very happy about the mindset, to be really calm at every moment. All the negative emotion doesn't affect me, and that was really a big part of taking the few opportunities I had in the tie-breaker and the first game I broke her in the second."
With the win, Garcia pockets $1.57million in prize money and 1,375 ranking points.
Her triumph in Fort Worth is the culmination of sparkling form that has seen her win every final she has played in 2022, while she has won eight of her last nine over the past six years.
It also marks a fine return to the top table. Back in 2017, 11 straight victories to win WTA 1000 events in Wuhan and Beijing saw Garcia first enter the top 10 and earn a maiden trip to the WTA Finals where she lost to Venus Williams in the semi-finals.
"Sometimes you are emotional or things don't go your way," Garcia said.
"I mean, sometimes there is a big fight, so you have to find your way through it. Some points, where you cannot do anything. You just try to put in the return and to run as fast as you can to the other side.
"And that was one of the biggest points I improved. Today one of the most important things was to stay calm and jump on every opportunity."
Sabalenka had knocked out top seed Iga Swiatek to reach the showpiece match but hit two costly double faults in the first-set breaker – an area that she has struggled with throughout the year.
"I just dropped my level for a little bit. On the tie-break and the first game of the second set. That's it," a rueful Sabalenka reflected.
"I did my best, [but] she played unbelievable tennis."
The fifth seed clinched her maiden spot at the season-ending WTA Finals on Wednesday and backed that up by securing her third WTA 1000 quarter-final on Thursday.
Gauff reeled off the first nine games of the match against Trevisan, where she triumphed in one hour and one minute. The 18-year-old came under pressure from Trevisan, who generated nine break points for the match but Gauff saved all bar one of them.
World number one Iga Swiatek (47) is the only player to have won more matches this year in straight sets than Gauff (32).
Gauff will face Victoria Azarenka in the quarter-finals after the Belarusian toppled 13th seed Madison Keys 6-4 6-7 (4-7) 6-1 in two hours and 13 minutes.
Two-time Australian Open winner Azarenka swept aside Keys in 32 minutes in the third set after a titanic battle in the opening two frames, winning 26 of the 37 final-set points. Azarenka's quarter-final appearance is her 34th since 2009, with only four players having more during the span; Agnieszka Radwanska (42), Simona Halep (39) and Caroline Wozniacki (36).
Third seed Jessica Pegula advanced to the last eight with a 6-4 6-4 victory over former US Open champion Bianca Andreescu.
The American, who survived three match points against Elena Rybakina on Wednesday, trailed early against the Canadian but took control of the match. Pegula will face Sloane Stephens in the quarter-finals after she toppled 2022 US Open semi-finalist Caroline Garcia 7-6 (8-6) 7-5.
On the day her WTA Finals berth was confirmed, seventh seed Daria Kasatkina lost 6-2 2-6 6-3 to Anna Kalinskaya in two hours and 14 minutes.
Fourth seed Maria Sakkari fought back to win 5-7 6-3 6-3 over 14th seed Danielle Collins, while Marie Bouzkova copped a bagel before triumphing 0-6 7-5 6-3 over Liudmila Samsonova.
Sakkari will next meet eighth seed Veronika Kudermetova who beat Jelena Ostapenko 6-4 6-4. Bouzkova will take on Kalinskaya in the last eight.
Badosa – the highest-ranked Spanish player in the women's draw – needed just 71 minutes to wrap up a 6-3 6-0 win over last year's Roland Garros runner-up, thrilling a supportive home crowd at the Manolo Santana Stadium.
Badosa edged a competitive start on the clay, with each of the first five games featuring break points, before the 25-year-old forced a series of errors from Gauff to take the opener.
The second set was far more straightforward, the error-prone Gauff rounding out the match by losing eight consecutive games to miss out on a spot in the last 16.
Gauff was not the only seed to be humbled on Saturday, with Caroline Garcia falling to a 7-6 (7-2) 6-3 loss in her meeting with Egypt's Mayar Sherif.
Sabalenka – the highest-ranked player in action on Saturday – enjoyed a more productive outing, however.
She saw off a spirited challenge from Colombia's Camila Osorio to clinch a 6-4 7-5 victory, teeing up a last-16 meeting with surprise package Andreeva.
Playing on her 16th birthday, wildcard Andreeva celebrated in style with a 6-3 6-3 win over Poland's Magda Linette, continuing a dream run which has also seen the Russian eliminate Leylah Fernandez and Beatriz Haddad Maia.
As the fifth seed, Garcia is by a distance the top-ranked French player in either the men’s or women’s singles but the country’s wait for a new grand slam champion goes on.
Blinkova, ranked 56, had never beaten a top-five player before but battled back from a set down to triumph 4-6 6-3 7-5, finally taking her ninth match point.
Nerves were clearly affecting the 24-year-old, who served for the match twice, while the partisan Philippe Chatrier crowd were willing Garcia on, but Blinkova did not let the opportunity for the biggest win of her life slip away.
Former world number three Elina Svitolina continued to impress in her comeback grand slam, taking inspiration from husband Gael Monfils as she saw off Australian Storm Hunter 3-6 6-3 6-1.
Less than 11 hours after completing an emotional five-set win over Sebastian Baez, Monfils was back at Roland Garros cheering on Svitolina.
“I watched him, but not live, I was screaming in my room,” said the Ukrainian. “It was an unbelievable match. I don’t know what he is doing here now, I think he should be resting, but I’m really thankful for him coming to support me, especially in this tough match.”
Svitolina is playing her first slam in more than a year following the birth of baby Skai last October.
The new mother and father are juggling the day job with childcare, and Svitolina said: “It’s the first tournament for us where we are both playing at the same tournament, and Skai is here with us in Paris as well. It’s really, really special.
“So far everything is going well and we really enjoy our time off the court together and on the court we try to be focused and play as good as we can.”
Svitolina is also having to put to one side thoughts of the troubles in her homeland and is using the situation to inspire her on court.
She said: “When I step on the court, I just try to think about the fighting spirit that all of us Ukrainians have and how Ukrainians are fighting for their values, for their freedom in Ukraine. And me, I’m fighting here on my own frontline.
“I cannot be sad. I cannot be distracted in some ways. I’m just going to lose. I have a flag next to my name so I’m fighting for my country, and I’m going to do that each time I step on the court.”
Third seed Jessica Pegula had an untaxing afternoon, taking the first set 6-2 against Camila Giorgi before the Italian pulled out.
Ninth seed Daria Kasatkina produced the shot of the tournament so far, a fizzing tweener winner, in a 6-3 6-4 victory over former finalist Marketa Vondrousova, while 2017 champion Jelena Ostapenko lost out 6-3 1-6 6-2 to American Peyton Stearns.
Hurkacz made it through a tough encounter against Stan Wawrinka 7-6 (7-5) 6-4 to give Poland a 2-1 lead in their Group B tie with Switzerland in Brisbane, before Linette came from behind to beat Jil Teichmann 5-7 6-4 6-1 to clinch it.
Poland will face Italy in the Brisbane final, whose 5-0 whitewash of Norway included Matteo Berrettini sealing victory with a 6-4 6-4 win over Casper Ruud.
In Perth, Croatia advanced to the City Finals after a dramatic day that saw Caroline Garcia get France on the board with a straight sets win against Petra Martic, before Adrian Mannarino came from a set down against Borna Gojo to serve for the match as he looked to bring his country level at 2-2.
However, Gojo broke back in a tense encounter before winning a deciding tie-break to send Croatia through to face Greece, who sealed a 4-1 win against Belgium.
Stefanos Sakellaridis recovered from going a set behind to beat Zizou Bergs, before Maria Sakkari overcame Elise Mertens 6-1 7-5, with Sakkari and Stefanos Tsitsipas adding some gloss to the score with a mixed doubles success against Kirsten Flipkens and Michael Geerts.
Spain and Australia were unable to progress but the hosts at least had the consolation of securing a victory thanks to wins for Jason Kubler against Albert Ramos-Vinolas, and the mixed doubles duo of John Peers and Sam Stosur against Jessica Bouzas Maneiro and David Vega Hernandez.
The USA had already secured their Finals berth against Great Britain in Sydney, but were ruthless as they finished off their tie against Germany to win 5-0.
After Jessica Pegula beat Laura Siegemund 6-3 6-2, Frances Tiafoe also defeated Oscar Otte in straight sets, before the American duo combined to beat Siegemund and Daniel Altmaier 6-7 (5-7) 6-4 10-7 to complete a clean sweep.
In a contest between two teenage stars, it was 17-year-old Gauff who sealed her second semi-final spot in as many weeks, having made the last four at the Internazionali d'Italia.
Third seed Gauff will face Katerina Siniakova next, after the Czech followed up her win over Serena Williams with a 7-5 6-1 defeat of Caroline Garcia.
"I was pretty satisfied with the way I played," Gauff said, after fending off Anisimova.
"I do think I could have served a little bit better, but other than that, I was pretty happy with the way I played."
Despite her valid concerns, Gauff won 72 per cent of points after landing her first serve and forced six breaks to win in style, reeling off six games on the trot from 3-0 behind in the second set.
The other semi-final will see second seed Wang Qiang take on Sloane Stephens.
Wang prevailed 7-6 (7-4) 3-6 7-5 against Petra Martic, while Stephens saw off Sara Errani 6-3 6-0.
It was another rain-affected day at the Serbia Open, where Maria Camila Osorio Serrano managed to get past Kamilla Rakhimova 4-6 6-3 6-4.
Anna Kalinskaya and Reka Luca Jani were locked at one set apiece in the only other match to get started before the weather halted play.
Muguruza, who won the WTA Finals title at the end of last season, was cruising at 6-0 3-0, but 31-year-old American Riske, despite tossing her racket in frustration, refused to give up. Incredibly, she won 12 of the next 13 games to reach the third round at the expense of the world number nine.
"After the first set, it literally could not get any worse," Riske said in her on-court interview following a 0-6 6-3 6-1 success.
"So if I could try to get two balls in the court we might get somewhere. I was just trying to hang in there. I've played Garbine many times before and it's always been a battle."
This was Riske's fifth match against Spanish star Muguruza, and despite losing the first two of those, she had since beaten the two-time grand slam winner twice, albeit most recently at the 2019 US Open.
"I felt if I could get in there a little bit, I was going to have my chances," Riske said. "I know I've beaten her before, and if I could just bring out some of my game, good things were going to happen."
It was world number 53 Riske's 10th career victory against a player ranked in the top 10.
British player Harriet Dart pulled off a shock win over Ukrainian Elina Svitolina, as the world number 122 snatched a 2-6 6-3 6-3 victory over the 12th seed.
Three of the biggest names in the draw took the long route through to the last-32 stage, with Emma Raducanu, Simona Halep and Iga Swiatek taken to a deciding set in their opening matches, having benefited from first-round byes
Raducanu fended off Caroline Garcia 6-1 3-6 6-1, while Halep was a 6-2 4-6 6-2 winner against Ekaterina Alexandrova, the Russian who is playing under a neutral flag.
Polish third seed Swiatek put a slow start behind her to beat Ukrainian Anhelina Kalinina 5-7 6-0 6-1 and is looking to build on her recent Qatar Open triumph. She said: "I'm pretty happy I could turn my head on to fight mode and stay focused, because that was the key I guess."
Last year's Wimbledon runner-up Karolina Pliskova bowed out, the Czech seventh seed losing 2-6 7-5 6-4 to Danka Kovinic of Montenegro.
The Tunisian overcame Australia's Ajla Tomljanovic in a 6-4 7-6 (7-4) victory at Arthur Ashe Stadium, before the Frenchwoman swept aside home favourite Coco Gauff 6-3 6-4.
In doing so, both have reached their first last-four appearance at the final grand slam of the year, and set themselves new benchmarks in the process.
Jabeur is the first Arab or African woman in the Open Era to make the semi-finals at Flushing Meadows.
On the back of reaching the final at Wimbledon earlier this year, she could finish the tournament as the world number two.
Garcia, meanwhile, has reached her first major semi-final without dropping a set along the way.
She has lost just 27 games en route and victory over Gauff extended her winning streak to 13.
In addition, she becomes just the third Frenchwoman to reach the US Open semi-finals in the Open Era, after Amelie Mauresmo and Mary Pierce.
Qualifier Varvara Gracheva earned her first career top-five win by beating 2022 Wimbledon and US Open finalist Jabeur 6-2 6-2 in only 67 minutes.
Fifth seed Caroline Garcia also crashed out, losing 6-2 6-3 to 74th-ranked Sorana Cirstea, having also recently beaten the Frenchwoman at Indian Wells.
Bianca Andreescu came from a set down to beat seventh seed Maria Sakkari 5-7 6-3 6-4 in a match that lasted over three hours.
Andreescu displayed some of the form that saw her lift the 2019 US Open title, fighting back from a set down and proving composed in the big moments.
The Canadian, who is ranked 31st, will take on 2020 Australian Open champion Sofia Kenin in the third round.
Second seed Aryna Sabalenka had few problems against Shelby Rogers, winning 6-4 6-3 in one hour and 17 minutes. Sabalenka will next face 31st seed Marie Bouzkova.
The 2023 Australian Open champion has won 65 main draw matches in WTA-1000 events, which equals Marion Bartoli and Ashleigh Barty at the 30th place since 2009 for the most wins at this level.
Indian Wells winner Elena Rybakina beat Anna Kalinskaya 7-5 4-6 6-3, and Petra Kvitova eased past compatriot Linda Noskova 6-3 6-0.
Ninth seed Belinda Bencic dropped just two games as she cruised past Leylah Fernandez 6-1 6-1, and will face Ekaterina Alexandrova next as the 18th seed needed three to get past Taylor Townsend.
Veronika Kudermetova was eliminated by Marketa Vondrousova 6-4 6-2, who goes up against Karolina Pliskova in round three after she eased past Wang Xinyu in straight sets.
The world number 26, who was defeated by Amanda Anisimova in the Melbourne Summer Set 2 semi-finals last week, beat second seed Muguruza 6-4 6-4.
Kasatkina held throughout the opening set, landing 67 per cent of her first serves, and saw the job through in the second despite a couple of early breaks for Muguruza.
It is the Russian's first win over a top-five opponent since beating Caroline Wozniacki at the 2018 French Open.
She will now face fifth seed Paula Badosa, who saw off Olympic gold medallist Belinda Bencic 7-6 (8-6) 3-6 6-3 in an entertaining match lasting two hours and 35 minutes.
The other semi-final in Sydney will be contested between Anett Kontaveit and Barbora Krejcikova, who advanced past Ons Jabeur and Caroline Garcia respectively.
Krejcikova proved far too strong for Garcia, prevailing 6-0 6-2 in 70 minutes, while Kontaveit was in action for just 43 minutes before being handed a walkover win in her match.
Jabeur had targeted "payback" against Kontaveit after her quarter-final opponent pipped her to the final WTA Finals spot in November, but injury cost her the chance to do so.
Having lost the first set 6-4, Jabeur – who eliminated Petra Kvitova in the previous round – felt unable to continue due to a lower back injury.
At the Adelaide International 2, three of the five Americans in action made it through to the semi-finals.
Alison Riske's clash with compatriot Madison Brengle ended early due to the latter retiring with the first set level at 3-3. Tamara Zidansek awaits Riske after beating Lauren Davis 7-6 (7-4) 7-6 (9-7).
Coco Gauff and Madison Keys will meet in the other semi-final, meanwhile, following victories over Ana Konjuh and Ludmilla Samsonova in two and three sets respectively.
Kenin is the top seed in France this week and belatedly secured her first WTA Tour victory since a major breakthrough in Melbourne.
The American had fallen at the first hurdle in both Qatar and Dubai in recent weeks, but she had no such troubles against Vitalia Diatchenko, advancing 6-4 6-3.
A pair of early breaks in the opener saw Kenin into a 4-1 lead, although opportunities for both players punctuated the contest.
The second set began with three straight games going against the serve, before Kenin settled the match at the second attempt with her sixth successful break point from 18 attempts.
Back on the winning trail, Kenin levelled her career record against Diatchenko at 1-1 after a second-round defeat at Wimbledon in 2018.
The only other round-of-32 clash on Wednesday saw France's Oceane Dodin overcome Mandy Minella in straight sets.
Meanwhile, Kenin's fellow seeds Caroline Garcia - a 7-5 6-2 winner against Ysaline Bonaventure - and Alison Van Uytvanck - triumphing over Viktoriya Tomova - enjoyed victories as they played last-16 matches.
But home hopeful Cornet fell short of the quarter-finals in a 4-6 7-6 (7-5) 6-2 reverse at the hands of Camila Giorgi.
Cornet led by a mini-break three times in the second-set tie-break, before Giorgi edged her opponent out and then dominated the decider.
Top seed Kontaveit overcame world number 61 Irina Bara in straight sets in her first-round clash and third favourite Krejcikova followed suit in her second-round match against Poland's Magdalena Frech.
Kontaveit will meet Sweden's Rebecca Peterson in the next round as she looks to set up a quarter-final meeting in Germany with eighth seed Andrea Petkovic, who defeated Misaki Doi 6-4 6-3 on Tuesday.
There was no such luck for ninth seed Elena Gabriela Ruse, though, after she lost 6-0 6-4 to last week's Budapest Grand Prix winner Bernarda Pera.
Swiss Joanne Zuger will next be the next challenge for Pera as she aims to reach a quarter-final clash against Katerina Siniakova, who triumphed 6-1 6-1 over Brazil's Laura Pigossi.
Putintseva is ranked as the second favourite in Italy and progressed with ease from her first-round clash against world number 147 Jaimee Fourlis, winning 6-3 6-1.
Seventh seed Anna Bondar had little difficulty beating Clara Burel 6-4 6-4, though Caroline Garcia and Nuria Parrizas Diaz faced more difficult tasks in their respective openers.
France's Garcia, the fifth favourite in Palermo, responded to a first-set scare to defeat compatriot Chloe Paquet, while eighth seed Parrizas Diaz also lost her opening set before downing Asia Muhammad.
Ukraine's Kostyuk prevailed in a closely contested battle against the highest seed remaining in the field, taking the only break of the first set after saving four Collins break points the game prior.
The two women traded breaks to begin the second set, but the 20-year-old Kostyuk was too strong down the stretch, winning five of the final six games.
It will also be the first WTA-level final for her opponent, with unseeded 22-year-old Russian Varvara Gracheva overcoming American Katie Volynets 6-4 5-7 6-4.
The two-and-a-half-hour clash was tight all the way through, with Gracheva only narrowly edging the total point count 101-94.
Meanwhile, down south of the border at the Monterrey Open, world number five Caroline Garcia won her semi-final against Elise Mertens 6-3 6-4.
The reigning WTA Finals champion will have a chance to collect the 12th singles title of her career, and her first of the season, when she meets Croatia's Donna Vekic in the final.
Vekic, the third seed, emerged the 7-5 6-2 victor against China's Zhu Lin, continuing a red-hot run of form that has seen her win 13 of her past 15 matches dating back to New Year's Eve.
Sixth seed Kudermetova showed great defiance to defeat American Collins 4-6 7-6 (7-5) 6-1 on Thursday.
Kudermetova fended off five match points when serving to stay in the tournament at 6-5 down in the second set and duly forced a tie-break.
Collins, runner-up to Ash Barty in the Australian Open final last year, took a 3-0 lead in the breaker, but back came her Russian opponent to level the match.
The world number nine dominated the deciding set to seal a meeting with Bencic in the last four.
Eighth seed Bencic got the better of WTA Finals champion Garcia 6-2 3-6 6-4.
Garcia broke straight back after going 3-1 down in the final set, but Bencic broke for the fourth time in the match to go through.
Paula Badosa and Daria Kasatkina will contest the other semi-final after beating Beatriz Haddad Maia and Petra Kvitova respectively.
Elisabetta Cocciaretto saved two match points as she came from a set down to beat Bernarda Pera 5-7 7-6 (10-8) 6-4 in the quarter-finals of the Hobart International.
The 21-year-old Italian will now face 2020 Australian Open champion Sofia Kenin, who also stormed back to defeat Anhelina Kalinina 4-6 6-3 6-1.
Lauren Davis and Anna Blinkova will do battle in the other semi-final following wins over Wang Xinyu and Yulia Putintseva respectively.
World number one Swiatek was already assured of her semi-final place heading into Thursday as Belinda Bencic's withdrawal had granted her a walkover.
She could watch on then as Kudermetova upset fourth seed Gauff 6-3 3-6 6-1 in Doha.
Swiatek has won each of her previous two matches against Kudermetova in straight sets, but the world number 11 will be on a high after her first top-10 win of the season.
It will be the 25-year-old's second semi of the season, although she withdrew from her Adelaide 2 match-up against Bencic.
While Gauff is out, there remains American representation as her doubles partner Jessica Pegula made light work of Beatriz Haddad Maia 6-3 6-2.
Pegula, the second seed, will face Greece's Maria Sakkari, who overcame third favourite Carolina Garcia 6-2 6-7 (5-7) 7-6 (7-5) in a battling encounter.
Gauff recorded five breaks of serve as she overcame Italian Camila Giorgi in routine fashion, a 6-2 6-3 triumph securing the third seed a place in the quarter-finals.
The American did have a few issues on her own serve, leading to seven double faults, but ended up winning in one hour and 11 minutes.
Martic, the second seed at the event, was made to work in the first set of her match against Ludmilla Samsonova, both players saving a break point on serve as it went the distance.
There was little to split the pair in the tie-breaker too, Martic edging it 7-5 as she capitalised on her first opportunity to take the set.
The second was more straightforward for the Croatian, an early beak of serve putting her in front before she repeated the trick to wrap up victory in the ninth game.
There were wins in straight sets for fellow seeds Caroline Garcia and Wang Qiang too, as they defeated Anna-Lena Friedsam and Martina Di Giuseppe respectively.
For Garcia, the triumph means a first quarter-final appearance in the 2021 season.
Sorribes Tormo was the only seeded player to exit in the day’s action, the Spaniard forced to retire at 2-2 in the deciding set against Sara Errani due to a problem with her left thigh.
"I'm very sorry for Sara. It was a battle, I know every time we play together it is like this. I was mentally ready to fight, to suffer," Errani said in her on-court interview.
Top seed Serena Williams is already out, beaten in straight sets by Katerina Siniakova to deal the 23-time grand slam champion a further blow ahead of this year's French Open.
Martic toppled the second seed with a 6-3 7-6 (7-2) victory on Friday.
The unseeded Croatian, who was beaten by eventual champion Elena Rybakina in the fourth round at Wimbledon last week, claimed the only break of the first set to lead 5-3 and held her nerve to serve it out.
Bencic twice came from a break down in the second set to force a tie-break, but Martic raced into a 6-0 lead and duly moved into the last four.
The 31-year-old Split native will come up against Garcia, who beat Sara Sorribes Tormo 6-4 6-1.
Frenchwoman Garcia also reached the last 16 in the grass-court grand slam at SW19 and has won 11 of her past 12 matches.
Unseeded duo Olga Danilovic and Anastasia Potapova will contest the other semi-final following victories over Simona Waltert and Wimbledon quarter-finalist Jule Niemeier respectively.
At the Budapest Grand Prix, Anna Bondar is through to the last four without dropping a set in her homeland after defeating Martina Trevisan 6-4 6-1.
Ninth seed Bondar will face Bernarda Pera, who beat Elisabetta Cocciaretto 6-4 6-3. Yulia Putintseva had won all eight games before Lesia Tsurenko retired from their quarter-final due to injury and she will take on Aleksandra Krunic, who cruised past Wang Xiyu 6-0 6-1.
Mertens, who reached the fourth round at Wimbledon at the start of July, succumbed to a 6-3 2-6 6-2 defeat to Magda Linette – her first loss to the Pole after three straight-set victories in their previous encounters.
The Belgian got just 52 per cent of her first serves in and won 38.5 per cent of points behind her second serve while only converting one of the five break points she earned.
Sixth seed Alison Van Uytvanck retired in the first set of her match against Dalila Jakupovic, while eighth seed Marie Bouzkova overcame Sinja Kraus 6-2 7-6 (7-2).
In Warsaw, fifth seed Garcia by no means had it easy in a 7-5 6-4 success over Doi.
The Frenchwoman committed eight double faults and only got 55 per cent of her first serves in, but by saving six of the eight break points she faced she was able to get the job done in straight sets.
Polish wildcard Maja Chwalinska was a 7-5 6-2 victor over qualifier Rebeka Masarova in only her second Tour-level tournament.
France's Garcia, the world number five and top overall seed, needed just 63 minutes to see off her Spanish challenger. She controlled the contest with her serve, taking the ace count eight to two while winning 75 per cent of her total service points (33-of-44).
She will now face Egypt's Mayar Sherif in the quarter-final after the seventh seed survived a tough 3-6 7-6 (8-6) 6-4 test from China's Wang Xinyu.
Fourth seed Elise Mertens emerged the 6-3 3-6 6-2 victor against Romania's Elena-Gabriela Ruse, while rising 22-year-old Italian Elisabetta Cocciaretto prevailed 7-6 (7-5) 7-6 (7-3) against Germany's Tatjana Maria.
North of the border in Austin's ATX Open, Danielle Collins ripped off a 67-minute 6-1 6-1 drubbing of Caty McNally to advance to the quarter-final.
Collins will meet Russia's Anna Kalinskaya next after the 24-year-old's convincing 6-3 6-1 victory over veteran CoCo Vandeweghe.
Eighth seed Marta Kostyuk is one of only three seeded competitors remaining after storming home in a 6-3 3-6 6-0 battle with Madison Brengle, and Germany's Anna-Lena Friedsam won the longest match of the day in a 7-5 6-7 (2-7) 7-6 (10-8) three-hour war of attrition against 18-year-old Russian Erika Andreeva.
