Barbora Krejcikova saved seven match points on her way to beating Anett Kontaveit in a thrilling Sydney Tennis Classic semi-final on Friday.

The world number four prevailed 0-6 6-4 7-6 (14-12) in a match that went the distance and will take on Paula Badosa, who beat in-form Daria Kasatkina in the other semi-final.

Krejcikova had lost five in a row against top-10 players and was soundly beaten in the first set, but she held in the second and earned the only break in the ninth game to level up. 

That set up an incredible decider, which fourth seed Kontaveit led 6-5, but she could not take the first three of her match points as Krejcikova battled valiantly to force a tie-break.

Krejcikova felt her opponent's pain as she then squandered two match points of her own when leading 6-4. 

It appeared neither player wanted to win as two more match points went begging for Krejcikova and four for Kontaveit in what turned into a real classic.

But Krejcikova eventually took her fifth opportunity to see off Kontaveit and reach a sixth WTA singles final.

"I think from both sides it was a really, really tough match," Krejcikova said. "I think we played wonderful tennis. 

"It was very, very tight, and I'm really happy that I was able to hold the nerves better and that I won this match.

"I was just playing, just trying to fight for every single ball. When I had those match points down, I was just trying to figure out how to build up the point and how to win the point."

Badosa awaits Krejcikova in Saturday's final after beating Kasatkina in a match with far fewer twists and turns.

Competing in her second semi-final in as many weeks, it was similar disappointment for Kasatkina as she fell to a 6-2 6-2 loss.

French Open quarter-finalist Badosa hit 26 winners to Kasatkina's 12 and did not look back after winning 14 of the opening 16 points.

At the Adelaide International 2, meanwhile, it will be an all-American final as Madison Keys and Alison Riske advanced past Tamara Zidansek and Coco Gauff respectively.

Riske was given a walkover win against Zidansek, who withdrew with an abdominal injury, while Keys beat compatriot Gauff in three sets.

Daria Kasatkina reached her second semi-final in as many weeks with a straight-sets victory over Garbine Muguruza at the Sydney Tennis Classic on Wednesday.

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.

World number one Ash Barty will start her 2022 season at the Adelaide International along with eight of the other current 10 top players in the world.

Barty has held top spot in the women's rankings since September 2019 and collected five titles – including Wimbledon – in the 2021 season but missed the French Open with a hip injury.

She also opted to not play in the season-ending WTA Finals in Mexico due to coronavirus-enforced quarantine concerns that could disrupt her preparation for the following campaign.

The Women's Tennis Association (WTA) confirmed on Friday that Barty would begin her 2022 season in Adelaide on January 2, along with defending champion Iga Swiatek, WTA Finals victor Garbine Muguruza and Roland Garros winner Barbora Krejcikova, as the world's elite players prepare for the Australian Open.

The entry list for the WTA 500 tournaments also includes Tokyo Olympics gold medallist Barbara Bencic, who finished runner-up to Swiatek in 2021, former world number one Karolina Pliskova and US Open runner-up Leylah Fernandez.

The field boasts 12 major trophies between them, but three grand slam winners will kick-start their seasons in Melbourne the day after.

Naomi Osaka, who is aiming to defend her title at the Australian Open, gets her preparations underway in the Melbourne Summer Set.

Two-time major winner Simona Halep and reigning US Open champion Emma Raducanu will play in the Melbourne Summer Set.

The trio are among 20 of the top 50 ranked players in the world for the two WTA 250 tournaments starting on January 3, with the entry list split between the competitions the week before matches start.

Raducanu will feature in just her eighth Tour-level event, and her fourth tournament since winning her first major, while Osaka will be appearing for the first time since an early defeat in the third round of the US Open to Fernandez.

Ash Barty has won the WTA's Player of the Year award for a second time, while Emma Raducanu's sensational 2021 season was capped with the Newcomer of the Year prize on Tuesday.

Barty collected the tour's top individual year-end award in 2019, having won the French Open and finished that season as the world number one.

And after Sofia Kenin succeeded her in 2020, Barty is back on top this year.

This was the third straight season the Australian superstar claimed the year-end number one ranking, and it saw her land a second major title at Wimbledon. Barty's five WTA titles in 2021 were unsurpassed.

But she has had to share the limelight in recent months with Raducanu, and that was the case again as the 19-year-old Briton was unsurprisingly hailed as the tour's star newcomer.

Raducanu became the first qualifier to win a grand slam when she swept to glory at the US Open, having also impressed in a run to the last 16 at Wimbledon.

The teenager, who has risen from 343rd to 19th in the rankings in the past year, won 10 straight matches without dropping a set from the first qualifying round to the final at Flushing Meadows.

Elsewhere, Roland Garros champion Barbora Krejcikova collected a pair of awards, scooping Most Improved Player and, alongside Olympic, WTA Finals and French Open-winning partner Katerina Siniakova, the Doubles Team of the Year.

Carla Suarez Navarro, who retired in 2020 and was then diagnosed with Hodgkin's Lymphoma, returned to the tour cancer free in 2021 for a farewell season and carried off the Comeback Player of the Year award.

Karolina Pliskova stayed in the hunt for a place in the last four of the WTA Finals with a 0-6 6-4 6-4 victory over Barbora Krejcikova, though her hopes hinged on Anett Kontaveit defeating Garbine Muguruza later in the day.

World number three Krejcikova did not have a win to her name in Mexico, losing to Kontaveit and Muguruza, but raced into the ascendancy on Sunday as she claimed the first set in just 26 minutes of an all-Czech tussle.

Pliskova, who had won both prior singles meetings between the pair, responded brightly in the second set before Krejcikova broke her fellow Czech's serve to take a 3-2 lead and seemingly edge closer to victory.

However, world number four Pliskova fought back by breaking in consecutive Krejcikova service games to level the match. The contest then teetered in the balance in the decisive set but, despite producing a double fault in the penultimate game, Pliskova downed Krejcikova to maintain hopes of an appearance in the final four in Guadalajara.

Wimbledon runner-up Pliskova won earlier in this tournament against Muguruza, who was set to face Kontaveit later on Sunday.

The 29-year-old Pliskova was sure to be paying close attention to that match. She needed Kontaveit, already through to the last four, to beat Muguruza and that would be enough to confirm the Czech's place in Group Teotihuacan's top two.

However, a win for Muguruza would see the Spanish sixth seed go through alongside Kontaveit, with Pliskova eliminated.

WINNERS/UNFORCED ERRORS 

Pliskova – 10/30
Krejcikova – 21/21

ACES/DOUBLE FAULTS 

Pliskova – 11/12
Krejcikova – 4/8

BREAK POINTS WON 

Pliskova – 3/8
Krejcikova – 4/11

Garbine Muguruza staved off elimination at the WTA Finals after the former world number one rallied past Barbora Krejcikova 2-6 6-3 6-4.

Having both lost their opening matches at the year-ending championship, sixth seed Muguruza and second seed Krejcikova went head-to-head in a crucial showdown in Guadalajara.

Muguruza dropped the opening set on Friday but completed a spirited comeback to stay alive in Mexico, where the two-time grand slam champion rallied from a set down to beat a top-three opponent for the first time since her triumphant Wimbledon campaign in 2017.

Spanish star Muguruza is still in the mix to progress to the semi-finals as she improved to 1-1 in Group Teohuatican, while Krejcikova dropped to 0-2.

French Open champion Krejcikova – who would have eliminated Muguruza with victory – raced through the opening set in 36 minutes, having converted all three of her break-point chances.

Muguruza, though, bounced back to claim a 4-1 lead and while Krejcikova battled, the former fired down five aces and hit 10 winners to level the match.

After exchanging holds, a monumental 12-minute game saw Muguruza – who would have ousted her opponent with a straight-set victory – break at the sixth time of asking and she maintained that momentum to close out the tense contest.

WINNERS/UNFORCED ERRORS 

Krejcikova – 26/33
Muguruza – 21/33

ACES/DOUBLE FAULTS 

Krejcikova – 8/4
Muguruza – 6/3

BREAK POINTS WON 

Krejcikova – 4/9
Muguruza – 4/10

Anett Kontaveit continued her superb form as she made a winning start at the WTA Finals against Barbora Krejcikova.

The Estonian was barely in the running for the year-ending championships during the first half of the season but, after losing a fifth match in a row on August 17, she went on a run of 26 wins out of 28, securing four titles and breaking into the top 10 for the first time.

Her confidence levels were still sky-high as she began her campaign in Guadalajara, dispatching French Open champion Krejcikova 6-3 6-4 to secure a Tour-leading 38th hard-court win of the season.

Like Kontaveit, Krejcikova – the only winner of a 2021 grand slam singles title at this year's Finals – was making her debut at this event, but she started in inauspicious fashion as she dropped serve in the fourth game after winning just one point against Kontaveit's serve in her opening two return games.

Kontaveit's powerful serving and groundstrokes kept her comfortably ahead in the first set, which she took at the second time of asking with an ace.

Krejcikova was broken again at the start of the second set. Her one opportunity to level, when a sublime drop shot put her 30-0 up on Kontaveit's serve, was snuffed out before she could muster a break point.

From then on, Kontaveit had the contest in her grasp, securing an 11th consecutive win when Krejcikova slapped a backhand into the net.

WINNERS/UNFORCED ERRORS

Krejcikova – 20/34
Kontaveit – 17/16

ACES/DOUBLE FAULTS

Krejcikova – 2/5
Kontaveit – 8/3

BREAK POINTS WON

Krejcikova – 0/0
Kontaveit – 2/3

The 2021 WTA Finals look set to be a fitting end to a fascinating season on the Tour.

The 50th year-ending championships, which will take place in Guadalajara instead of Shenzhen due to coronavirus restrictions, will see eight of the top-10 ranked players come together in two round-robin groups, with four semi-final places up for grabs.

Six of the eight competitors will make their debuts at the event, while only two grand slam finalists from this year – and just one champion – will be present. With world number one Ash Barty withdrawing because of concerns around possible quarantine issues, it really does feel like an open draw.

Stats Perform looks at the eight Finalists and the key data you need to know before the action gets underway...

Group Chichen Itza

Aryna Sabalenka (1)

World number two Sabalenka is the top-ranked competitor in Guadalajara, with 44 match wins this year and titles in Abu Dhabi and Madrid, where she beat Barty.

The Belarusian boasts formidable weapons: Sabalenka has won 71.1 per cent of first-serve points and has an average of 8.4 forehand winners per match on the Tour this season, both of which are best figures among the eight Finalists.

She has only played two matches since losing to Leylah Fernandez in the US Open semi-finals, though, both of which were at last month's Kremlin Cup in Moscow.

Did you know? Since the start of 2018, Sabalenka has won the joint-most matches (three) in WTA Tour main draws after losing the first set 0-6. At the same time, she is 9-13 in three-set contests in 2021.

Maria Sakkari (4)

The nearly-woman of 2021, Sakkari has reached more semi-finals this year (seven) than anyone else on the WTA Tour, including at two of the four slams, but made it to just one final (in Ostrava, where she lost to Anett Kontaveit).

Still, this has been a historic year for the 26-year-old, who became the first Greek woman to reach a major semi-final, enter the top 10 and qualify for the season-ending championship.

Since the start of the US Open, Sakkari has lost only four of 14 matches, a run that includes the semi-final of the Kremlin Cup where she retired due to dizziness.

Did you know? Nobody has won more Tour-level matches against top-10 opponents this year than Sakkari (seven, level with Barty and Jessica Pegula). Before 2021, her record in such matches was 10-13.

Iga Swiatek (5)

Swiatek, the 2020 French Open champion, is the youngest competitor at these Finals at 20 years and 170 days old (as of the tournament's end). She is just the second player born this century to reach this event, after Bianca Andreescu in 2019.

Although unable to get beyond the quarter-finals of a major this year, Swiatek did win titles in Adelaide and Rome, where she inflicted a double bagel on Karolina Pliskova in the final.

Her success in Australia was her first on a hard court, a surface on which she won 19 of 28 matches this year.

Did you know? Swiatek has won 58 per cent (28 of 48) of her matches this season in straight sets, the highest ratio among the Finalists.

Paula Badosa (7)

A successful year for Badosa has been built on clay: she won a Tour-leading 17 matches on the dirt in 2021, reaching the French Open quarter-finals, the last four in Madrid and Charleston and winning the title in Belgrade.

This has been a breakthrough season for the 23-year-old across all surfaces, though, one that culminated in a record-breaking three-set win over Victoria Azarenka in the final at Indian Wells last month.

Badosa clinched that match after a third-set tie-break. She has won four deciding sets in that fashion this year, the most of anyone on the WTA Tour.

Did you know? Badosa has won seven matches (excluding the Olympics) after dropping the first set in 2021. Nobody else has as many come-from-behind victories among the Finalists.

Group Teotihuacan

Barbora Krejcikova (2)

The only major singles champion from 2021 at these Finals, Krejcikova has enjoyed a remarkable rise this year.

Along with success at Roland Garros, where she also triumphed in the doubles, the Czech won titles in Strasbourg and Prague; only world number one Barty (five) and Kontaveit (four) have won more this year.

Among the eight finalists, Krejcikova boasts the highest break-point conversion ratio (49.7 per cent, or 142/286) and break-point saved figure (66.4 per cent, or 150/226) for this season. She has become a clutch competitor and will be hard to stop in Mexico, both in the singles and the doubles.

Did you know? Krejcikova has won six matches against top-20 opponents in her career. All six of those wins were in 2021.

Karolina Pliskova (3)

Pliskova boasts impressive experience of the year-ending event: she is only the fourth player to qualify for five or more WTA Finals since the current format was introduced in 2003 (after Agnieszka Radwanska, Petra Kvitova and Azarenka).

Beaten in her three Tour finals this year, including Wimbledon, the 29-year-old will be desperate to go at least one better than her three consecutive semi-final appearances at this event.

Pliskova begins against Garbine Muguruza, a player she has beaten twice before at the season-ending tournament.

Did you know? Pliskova leads the Tour for aces this season with 364, hitting a year-best 21 in her round-of-16 match with Jelena Ostapenko in Stuttgart. It's the fourth time in the past six seasons Pliskova has been top of the aces standings.

Garbine Muguruza (6)

This is the first time since 2000 that two Spanish players have contested the Finals. Back then, it was Conchita Martinez and Arantxa Sanchez Vicario at Madison Square Garden in New York.

Muguruza, champion in Dubai and Chicago this year, has won more matches on hard courts (34) than anyone else in 2021 aside from Kontaveit. She also boasts the best average for successful net approaches this year (3.0) among the Finalists, which will make her a challenging obstacle in what will be her first Finals since 2017.

The former world number won made a career-high four Tour finals this year and won more than one trophy in a season for just the second time, sending her back into the top 10 for the first time since 2018. 

Did you know? Muguruza boasts a 10-1 record in WTA tournaments in Mexico, winning back-to-back titles in Monterrey in 2018 and 2019.

Anett Kontaveit (8)

With a Tour-leading 37 hard-court wins this year and on a formidable run of form, Kontaveit could spring a surprise at her first Finals.

After losing her fifth match in a row to Ons Jabeur on August 17, the Estonian went on a run of 26 wins from 28 matches, lifted four titles and broke into the top 10 for the first time. It was Jabeur she edged out for a place at this tournament after she won her fourth title of the year at Cluj-Napoca.

Along with Barty, Kontaveit is the only player to reach six Tour-level finals this year, while nobody at the season-ending tournament has won more titles (four).

Did you know? Kontaveit has hit the most backhand winners (293) on hard courts on the WTA Tour in 2021, averaging nearly six per match.

Australia and Switzerland secured their spots in the semi-finals of the Billie Jean King Cup and will go up against each other for a place in the final.

Belarus proved no match for Australia, who got the job done across their two singles matches on the day in the Czech Republic.

Storm Sanders got the ball rolling as she comfortably saw off Yuliya Hatouka 6-3 6-3 in the first contest of the day in Group B.

Ajla Tomljanovic was made to work a little harder by Aliaksandra Sasnovich as she lost the first set but eventually rallied to overcome her opponent 4-6 6-2 6-3.

It meant the two countries' doubles meeting was a dead rubber – Belarus at least took the opportunity to avoid a 3-0 annihilation as Sasnovich teamed up with Lidziya Marozava in the 6-4 6-4 defeat of Olivia Gadecki and Ellen Perez.

In Group D, Switzerland and the Czech Republic claimed one victory apiece in the singles – Marketa Vondrousova had too much for Viktorija Golubic in a 6-4 6-2 success that gave the Czechs the upper hand.

But Belinda Bencic levelled things up despite the unenviable task of facing world number three Barbora Krejcikova, emerging with a 7-6 (7-2) 6-4 success.

Bencic was then involved in the doubles decider as well, getting the better of Lucie Hradecka and Katerina Siniakova with Jil Belen Teichmann, their 6-3 6-3 win sealing the semis spot for the Swiss.

The Russian Tennis Federation – who eliminated defending champions France on Wednesday – and the United States are due to contest the other semi-final.

Iga Swiatek was knocked out of the Indian Wells Open in the round of 16, the second seed headlining the list of casualties on Tuesday.

Swiatek was swept aside by Jelena Ostapenko in the battle between two previous French Open champions in the desert.

Elina Svitolina, reigning Roland Garros champion Barbora Krejcikova and US Open runner-up Leylah Fernandez were also sent packing from the WTA Premier 1000 event.

SWIATEK CRUMBLES

After top seed Karolina Pliskova was eliminated on Monday, 2020 French Open champion Swiatek crashed out following a 6-4 6-3 defeat to Ostapenko.

Ostapenko – the 2017 Roland Garros winner – rallied from a break down in each set to reach the quarter-finals at Indian Wells, where the 24th seed hit 25 winners to 21 unforced errors in 93 minutes.

"I knew it was going to be a very tough match because she's such a great player, she won a grand slam and she's playing great tennis," Ostapenko said.

Standing in the way of Ostapenko and the semi-finals is Shelby Rodgers, who edged Flushing Meadows finalist Fernandez 2-6 6-1 7-6 (7-4).

SVITOLINA UPSTAGED BY PEGULA

Svitolina's campaign in the desert did not go according to plan, the fourth seed crushed 6-1 6-1 by Jessica Pegula.

Pegula – the 2021 Australian Open quarter-finalist – dismantled Svitolina in just 68 minutes for her seventh last-eight appearance of the season and fourth at WTA 1000 level.

"I think I've just been making a lot of really good decisions in the right moments," said Pegula, who will face two-time grand slam champion Victoria Azarenka following her seventh top-10 victory. "That obviously comes with playing a lot of matches, winning and getting confidence... it's just been more belief that I can play at this level. I think this year, I realised that, and I've been having good results."

KERBER POWERS THROUGH AS KREJCIKOVA FALLS

Three-time major winner and 10th seed Kerber will feature in the quarter-finals after overpowering Ajla Tomljanovic 6-4 6-1.

Kerber will next meet 21st seed Paula Badosa, who shocked third seed and reigning French Open champion Krejcikova 6-1 7-5.

"I think I played a pretty good match today," Badosa said. "I knew I had to play on a high level against Barbora. She's an amazing player, very talented. We played before so I knew what I was going to find there on court. I'm feeling good and I'm very happy that I could play my best today."

Top seed Karolina Pliskova suffered a shock defeat while defending champion Bianca Andreescu and Coco Gauff also were on the wrong end of upsets Monday at the Indian Wells Open. 

World number 115 Beatriz Haddad Maia of Brazil stunned Pliskova in straight sets to reach the round of 16 at a WTA Premier 1000 event for the first time.

The 15th and 16th seeds, Gauff and Andreescu, also exited in two sets, albeit to seeded players. 

LUCKY LOSER OUSTS PLISKOVA 

Haddad Maia lost in the final round of qualifying but made the main draw as a lucky loser when Nadia Podoroska withdrew through injury, and she has made the most of that reprieve with a 6-3 7-5 defeat of the world number three. 

She had faced Pliskova once before and it did not go well, a 6-1 6-1 rout at the 2018 Australian Open, but the Czech struggled to find her trademark serve amid powerful winds in the California desert.

Pliskova suffered 12 double faults and won just 43.4 per cent of points on her serve, whole Haddad Maia saved nine of the 14 break points she faced on her own serve. 

KONTAVEIT STAYS HOT TO DETHRONE ANDREESCU

Haddad Maia next faces 18th seed Annett Kontaveit, who ousted Andreescu 7-6 (7-5) 6-3 to end the Canadian's dreams of a repeat. 

Kontaveit has won 15 of her last 16 matches, winning titles in Cleveland and Ostrava during that stretch. Monday, she captured the first set on her fifth set point before rallying from a 3-1 deficit in the second to run the table and seal the win.

"It was extremely close throughout the match and I was just trying to stay tough. I was ready for a tough match," Kontaveit said. "She's such a good player, such a great competitor, so I knew it wasn't going to be over until it was really over."

BADOSA BOUNCES GAUFF

Paula Badosa, the 21st seed, breezed past Gauff 6-2 6-2 as the American teen also had trouble with her serve, hitting just two aces after recording 12 in her previous match. 

In a meeting of the last two defeated finalists in the tournament, 10th seed Angelique Kerber beat 20th seed Daria Kasatkina 6-2 1-6 6-4. 

Third seed Barbora Krejcikova handled Amanda Anisimova with ease, 6-2 6-3. 

Ons Jabeur, the 12th seed, had little trouble in downing 22nd seed Danielle Collins 6-1 6-3. 

Aryna Sabalenka has ranked among the top dozen players in the world since 2018, but her grand slam results always seemed underwhelming. 

In 12 career majors heading into 2021, Sabalenka had advanced past the third round only once, a fourth-round exit at the 2018 US Open. 

Now she is into her second successive grand slam semi-final after defeating Barbora Krejcikova 6-1 6-4 Tuesday, and she said the adjustments she has made this year have paid off. 

"I think I improved my volley game, my slice game," Sabalenka told ESPN after her latest win. "I mean, I would like to say my service game [too] but today's didn't work well."

She added with a smile: "I don't know, maybe the court's a little bit smaller, I don't know, I need to check it. But, yeah, I improved a lot."

Indeed, Sabalenka won seven of eight net points (to eight of 14 for her opponent) and consistently won points on her first serve even though it did not go in as often as she would have liked. 

Sabalenka entered the match having won 82 per cent of points on her first serve in the tournament and was down to 76 per cent Tuesday as she got only 57 per cent of her first serves in the court, but that was plenty good enough to handle Krejcikova. 

She said she focussed on putting as many balls back in play as she could and believed that was the key to her victory, as her opponent had 29 unforced errors and just 14 winners. 

Though the match was rather one-sided, Sabalenka enjoyed the support of the crowd in her first time playing Arthur Ashe Stadium during the night session. 

"I really love to be in New York and the US Open, one of my favourite slams, and I'm really enjoying my game here and every second on this court," she said. 

She also knows she probably will not get the same level of fan support in the semi-final, where she will face Canadian teen sensation Leylah Fernandez. 

"She's playing well, she's moving well and the crowd here [is] for her so I would say it's like nothing to lose for her," Sabalenka said. "It's going to be interesting match and I'm really looking forward to this one."

Aryna Sabalenka is into the semi-finals at a second successive grand slam after making easy work of Barbora Krejcikova at the US Open on Tuesday. 

The second seed cruised past eighth-seeded Krejcikova 6-1 6-4 to set up a semi-final meeting with Canadian teen Leylah Fernandez at Flushing Meadows. 

Sabalenka is coming off a semi-final appearance at Wimbledon, her best career result in a major, and she was rarely tested in her quarter-final rout of Krejcikova.

The pair appeared evenly matched heading in, both having won 42 matches this year with Krejcikova taking three tournament titles – including Roland Garros – and Sabalenka two. But there was a clear separation between the pair on this night at Arthur Ashe Stadium. 

Sabalenka started strong, breaking Krejcikova in her first service game to take an early lead and never looking back as she hit 12 winners to the Czech's five in the opening set.

Krejcikova lost her last chance to salvage the first set in the sixth game, as she double-faulted on the fourth break point she faced in the game to give Sabalenka a 5-1 lead before the Belarusian had an easy hold to secure the set. 

The second set featured more of the same as Sabalenka broke her opponent in the opening game, dropping only one point as Krejcikova imploded with three unforced errors and a double fault. 

Sabalenka was not quite as sharp as the set unfolded, falling behind 0-30 in consecutive service games, but she fought back to win both without facing a break point. 

While Krejcikova stablised on her own service games, the damage was done. Sabalenka served out the match without dropping a point, capping her triumph with an ace. 

Data Slam: Sabalenka top winner on Tour

The victory was Sabalenka's 43rd match win of the year against 14 losses, breaking a tie with Krejcikova (42-11) and Ash Barty (42-8), both of whom have won grand slam titles this season, for the most WTA Tour wins in 2021. 

WINNERS/UNFORCED ERRORS

Krejcikova – 14/29
Sabalenka – 22/23

ACES/DOUBLE FAULTS

Krejcikova– 4/5
Sabalenka – 6/7

BREAK POINTS WON

Krejcikova – 1/6
Sabalenka – 4/10

Barbora Krejcikova explained she was hit by breathing difficulties and a spell of severe dizziness as she overcame Garbine Muguruza at the US Open.

French Open champion Krejcikova – who is making her main-draw debut at Flushing Meadows – had to hold off a fightback from former world number one Muguruza on Sunday to progress into her first US Open quarter-final with a 6-3 7-6 (7-4) victory.

However, Muguruza was left angry after Krejcikova started to take more time in between points.

After saving three set points at 4-5 down in the decider, Krejcikova went off court for medical treatment, before returning to see out the match on a tie-break.

Muguruza appeared to confront Krejcikova during the post-match handshake, and the Spaniard told the media: "I'll let you guys judge what you think about this.

"I think, between players, you know a little bit how to behave in certain moments and I wasn't very happy at the end of the match."

Krejcikova, however, explained how she had suffered during the match.

"I think I started the match really well and was playing good tennis," Krejcikova said, according to the WTA. 

"The key was to start the match well. There were a lot of breaks, which was difficult, but I was happy that I won the first set 6-3. Out of nowhere I got the lead 4-0 and then things started to get complicated.

"Garbine started to raise her level and I was expecting that. At the end I was really struggling and I feel really bad right now.

"I don't really know what happened, but I couldn't breathe. I started to feel dizzy and the whole world was shaking. It never happened to me before."

Krejcikova also needed medical attention after the match and did not hold a post-match news conference.

The Czech has now won 29 of her last 32 matches and will face Aryna Sabalenka, the highest seed remaining at Flushing Meadows, in the quarter-finals. 

Ash Barty reached her sixth semi-final of the year after winning the battle of grand slam champions against Barbora Krejcikova at the Western & Southern Open.

World number one and top seed Barty – the Wimbledon titleholder – dispatched French Open champion Krejcikova in straight sets in Cincinnati on Friday.

Another slam champion awaits Barty in the form of Angelique Kerber, while wildcard Jil Teichmann continued her fairytale run with victory over Olympic gold medallist Belinda Bencic.

Coffee the tonic for in-form Barty

Australian star Barty was too good for Krejcikova, winning 6-2 6-4 at the WTA 1000 tournament.

Barty had to battle from a break down in the second set against the fast-rising Krejcikova, who has shot up from 65th in the world to a career high of number 10 this year.

After extending her season record to 38-7, Barty talked about the importance of drinking coffee in the morning.

"I travel with a French press and an AeroPress, just to have two options. Usually every tournament we go to, one of us has a cafe that we have been to before, so I have got a little section of all my local cafes from the tournaments, so we try and get out to those if we can," she said.

"This year, some places we haven't been able to; some places we have. It's been nice to get some sort of a mixture, but I'm pretty simple. I'm just a black coffee cup in the morning, and then I'm set."

Three-time major champion Kerber is next up after she was 6-4 3-3 ahead before Petra Kvitova retired hurt due to a stomach problem.

Teichmann takes down another star

Unheralded Swiss and world number 76 Teichmann claimed another scalp, this time upstaging countrywoman Bencic 6-3 6-2 in the quarter-finals.

Teichmann stunned world number two Naomi Osaka en route to the quarters and maintained her giant-slaying form in Cincinnati, where 10th seed Bencic became the latest victim.

"We hugged before the match; we hugged after the match," Teichmann said of the Bencic meeting. "We know that once we step on court it's business, it's just another player I have to deal with, and she had the same mindset. At the beginning it's obviously a bit special, but once we're in it, we just look at the game, not looking at the opponent, or at least I do that way."

Teichmann will take on fifth seed Karolina Pliskova, who advanced to her second successive WTA 1000 semi-final after Paula Badosa retired down 7-5 2-0.