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.

Ash Barty and Angelique Kerber set up a blockbuster Western and Southern Open semi-final – but Petra Kvitova suffered a fitness scare ahead of the US Open.

World number one Barty won 6-2 6-4 against French Open champion Barbora Krejcikova, who she also defeated in the fourth round during her Wimbledon title run last month.

Kerber and Kvitova then battled it out for the right to tackle Barty in the last four, but a quarter-final that was building momentum ended prematurely when two-time Wimbledon winner Kvitova found a recent stomach problem too troublesome.

Kerber was 6-4 3-3 ahead in the contest, having recovered from being an early break down in the second set, getting her game together as 31-year-old Kvitova began to suffer.

During an injury timeout, which Kvitova called after the fifth game of the second set, the Czech received a massage to her abdominal region and played on briefly, before walking up to the net to concede the match.

It remains to be seen whether the setback in Cincinnati might have consequences for her involvement at Flushing Meadows, with the US Open due to begin on August 30.

Kvitova wrote on Twitter minutes after coming off court: "I stayed out there as long as I could. I have been struggling with a stomach issue for several days and unfortunately couldn't finish the match today. Good luck Angie - sorry to end it that way - and can't wait for the next battle with you."

Kerber said in an on-court interview: "Of course, this is not the way you would want to win the match. I hope Petra will recover as fast as possible and be ready for the US Open.

"I know she's a big fighter and fights until the last points, so I hope she is not too bad and hope she is fine really, really soon."

Kerber has now won 14 of her last 15 matches, with the exception being her Wimbledon semi-final defeat to Barty.

Barty got through in a more routine manner on Friday, albeit having 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.

Barty said: "Barbora served exceptionally well early in that second set and was able to take advantage of a service game of mine where I just hit too many second serves.

"I wanted to try and get a little bit more positive on her service games and then try to get myself in the points a little bit more. I'm happy to run away with that one in the end."

Two-time US Open champion Venus Williams has been given a wildcard entry to participate in this year's tournament.

The 41-year-old American will be making her 23rd appearance at Flushing Meadows and a 15th in a row.

Williams, who has not missed a grand slam since Wimbledon in 2013, is one of eight wild card selections for the women's singles draw.

Former semi-finalist CoCo Vandeweghe and Emma Navarro are joined by teenagers Hailey Baptiste, Ashlyn Krueger, Caty McNally and Katie Volynets.

Storm Sanders has been awarded a reciprocal wild card in agreement with Tennis Australia.

Naomi Osaka will be looking to defend her title in New York, with the main draw scheduled to run from August 30 to September 11.

Simona Halep says she is no longer afraid of coronavirus after getting vaccinated and hopes more players will take the jab.

Halep opted against travelling to New York for the US Open last year due to the pandemic before testing positive for COVID-19 last October.

The two-time grand slam champion missed the French Open and Wimbledon this year with a torn calf muscle, but claimed her first win since May at the Western and Southern on Tuesday, beating Magda Linette 6-4 3-6 6-0.

Former world number one Halep revealed she feels much more comfortable back on the circuit after taking the vaccine.

"I don't feel afraid, because I am vaccinated," The Romanian told reporters. "I feel protected. I am taking care. I wear the mask when many people are around."

Players have faced strict protocols since the tour resumed, with the challenges of staying in biosecure bubbles and playing in empty stadiums last year before restrictions gradually eased.

Stefanos Tsitsipas this week said that he would only take the vaccine if it becomes mandatory to play on the ATP Tour after Novak Djokovic stated he hopes it will not become a requirement to take the jab.

Halep hopes fellow professionals take the vaccine so they do not face such strict protocols.

"I don't like the bubbles," Halep said. "I feel very stressed when I'm in the bubble.

"So if people can vaccinate more and more (it) will be better, because we will not have more restrictions anymore."

Simona Halep, a three-time runner up in Cincinnati, claimed her first win since May by overcoming Magda Linette 6-4 3-6 6-0.

The 12th seed has just returned from a calf muscle tear which saw her miss the French Open and Wimbledon, and was defeated by Danielle Collins in Montreal last week.

However, at 1-4 down in the second set she required medical attention for what she described as a "sharp pain" in her right leg, but after a rain delay, the Romanian came out of the blocks to claim a third-set bagel.

Halep progressed to the Round of 32 where she will play American Jessica Pegula.

Sunday's breakthrough National Bank Open winner Camila Giorgo was beaten in straight sets by Pegula 6-2 6-2.

Former world number one Victoria Azarenka needed only one hour and nine minutes to dispose of Ludmilla Samsonova and seal her spot in the last 32.

The Belarussian triumphed 6-2 6-3 over the Russian, dominating her first serve and breaking Samsonova five times throughout the match.

Tokyo 2020 gold medalist Belinda Bencic eased past Marketa Vondrousova 6-3 7-5 continuing her bright recent run, winning in one hour and 27 minutes.

In the final match of the day's play, Caroline Garcia defeated 2017 U.S. Open champion Sloane Stephens 7-6 (9-7) 4-6 6-4 in two hours and 33 minutes.

Dayana Yastremska, Bernarda Pera, Karolina Muchova, Ons Jabeur, Elena Rybakina, Veronika Kudermetova and Coco Gauff were all winners too.

Petra Kvitova was one of a handful of seeded players to take the court at the Western and Southern Open on Monday and came away victorious against a past champion of the event. 

The 11th-seeded Kvitova defeated 2019 Western and Southern winner Madison Keys 7-5 6-4 on a rain-plagued opening day of main-draw play at the tournament outside Cincinnati, Ohio. 

The Czech saved eight of nine break points against her serve while breaking Keys three times, and that was enough to pull out the victory. 

Kvitova's countrywoman Barbora Krejcikova, the ninth seed, made her singles debut at the WTA 1000 event with a 6-3 6-2 rout of Daria Kasatkina. 

Fifteenth seed Elise Mertens also was a straight-sets winner, taking down Nadia Podoroska 6-3 6-4, while 13th seed Jennifer Brady defeated Ekaterina Alexandrova 6-3 7-6 (7-3) in a match that finished shortly before 1 a.m. local time.

Though only Krejcikova was in action Monday, the field in Cincinnati includes nine of the top 10 players in the rankings, led by Ashleigh Barty and Naomi Osaka in their first appearances since the Tokyo Olympics. 

In other matches on the first day of play, Heather Watson defeated Aliaksandra Sasnovich 6-2 3-6 6-1, while Paula Badosa outlasted Petra Martic 4-6 6-4 7-6 (11-9) in a two-hour, 34-minute marathon. 

Yulia Putintseva breezed past Zhang Shuai 6-2 6-0, Jelena Ostapenko beat Tamara Zidansek 7-5 6-1 and Jil Teichmann downed Sorana Cirstea 6-2 6-0. 

Angelique Kerber beat Maria Sakkari 6-2 6-2, with Alison Riske matching that scoreline in a defeat of Leylah Fernandez.

Shelby Rogers won 6-4 2-1 when her countrywoman Danielle Collins retired with an injury. 

Naomi Osaka was reduced to tears on Monday in her first WTA Tour news conference since snubbing the media at the French Open.

Osaka withdrew from the second grand slam of the year at Roland Garros almost three months ago after declaring she would not fulfil press conference duties during the tournament.

The four-time major champion cited mental health concerns for reaching that decision and skipped Wimbledon before returning to action at the Tokyo Olympics on home soil.

Osaka, who revealed in Paris she had suffered "long bouts of depression" since winning the US Open in 2018, agreed to speak to the press as she prepares return to the WTA Tour at the Western and Southern in Cincinnati this week.

The world number two was emotional after being asked how she benefits from a high-media profile but does not like talking to media.

Osaka answered the question from the journalist, but the video call was paused as she cried before later resuming the press conference.

She said before pausing: "That's interesting: I would say the occasion, when to do the press conferences is what I feel is the most difficult.

"I'm actually very interested in that point of view. For me I feel this is something I can't really speak for everybody, I can only speak for myself.

"But ever since I was younger, I've had a lot of media interest on me, and I think it's because of my background as well as how I play.

"Because in the first place I'm a tennis player, which is why a lot of people are interested in me. So I would say in that regard I'm quite different to a lot of people, and I can't really help that there are some things I tweet or say that create a lot of news articles or things like that.

"But I would also say, I'm not really sure how to balance it too, I'm figuring it out at the same time as you are, I would say."

Osaka then broke down while the next question was being put to her, but was able to continue.

The 23-year-old was given a first-round bye in what will be her first WTA tournament since the French Open.

Unseeded Camila Giorgi again surprised Karolina Pliskova as she earned a straight-sets win in Sunday's National Bank Open final to claim the third singles title of her career.

The world number 71 defeated Pliskova at the Viking International and the Tokyo Olympics in the past three months and prevailed 6-3 7-5 in their latest meeting in Montreal.

Giorgi, who had never previously won a trophy above 250 level or on outdoor hard courts, has now triumphed in 16 of her last 20 matches in an impressive 2021 campaign.

She lost just one set all week and will move back into the world's top 35 for the first time since May 2019 with this first tournament victory since the Linz Open in October 2018.

Fourth seed Pliskova eliminated favourite Aryna Sabalenka in the semi-finals but could not replicate that performance as she fell at the final hurdle in a tournament for the third time this year.

Giorgi broke the former world number one for the first time in a lengthy fifth game and took the first set when Pliskova double faulted and sent a forehand wide in the final game.

Pliskova double faulted six times across the match, which lasted one hour and 40 minutes, including in the fourth game of the second set to put her opponent in complete control.

The Czech was given hope when earning her first break of serve in the following game, but she was let down by some forehand errors in the 12th game and Giorgi took her second championship point to seal an emotional win.

Karolina Pliskova will face unseeded Italian Camila Giorgi in the National Bank Open final after beating top seed Aryna Sabalenka in the last four.

An intriguing semi-final pitted two of the favourites against one another in Montreal and it was Pliskova, the fourth seed, who came out on top 6-3 6-4.

The Wimbledon finalist broke early in the first and then clinched the set on Sabalenka's serve, too, although she was made to work a little harder in the second.

Pliskova fell behind in the seventh game, but she responded by winning three straight games to wrap up victory.

"It's an amazing feeling to be in another final this year," Pliskova said.

"I think I was super solid today. I just did everything what I was supposed to do to win this match, played smart.

"My serve was pretty good, I have to say."

Indeed, the Czech landed 71 per cent of her first serves in – with 10 aces to two double faults – helping her to win 69 per cent of her service points.

World number 71 Giorgi progressed to the decider with a three-set win over Jessica Pegula in two hours and 11 minutes.

The 6-3 3-6 6-1 win means the Italian qualified for her first career WTA 1000 final.

Giorgi had toppled seventh seed Petra Kvitova, ninth seed Elise Mertens and 15th seed Cori Gauff on her route to the decider.

Local hope and reigning champion Bianca Andreescu blew an early lead as she was toppled by Ons Jabeur in the Round of 16 at the National Bank Open in Montreal.

Tunisian 13th seed Jabeur defeated the Canadian second seed 6-7 (5-7) 6-4 6-1 in two hours and 39 minutes on Thursday.

The come-from-behind triumph was the second time in two matches that the Tunisian has rallied from a set down to win after beating Daria Kasatkina in three.

Jabeur had twice been a break up in the opening set before Andreescu claimed it in an tiebreak.

The 26-year-old Tunisian, who made the Wimbledon quarter-finals this year, responded by breaking at 5-4 to win the second set.

After Andreescu had an injury scare after landing awkwardly on her left foot late in the second set, Jabeur dominated the third, finishing by winning eight of the final nine games.

Jabeur finished with 9-3 aces and was more effective on serve, going at an 81.6 win percentage on her first serve (40 from 49 points).

The lower side of the draw has opened up for the Tunisian who will face Jessica Pegula in the quarter-finals after the unseeded American defeated countrywoman Danielle Collins 6-4 3-6 7-5.

Two-time Wimbledon champion and seventh seed Petra Kvitova was knocked out in a shock by Italian Camila Giorgi in straight sets.

Giorgi, ranked 71st in the world, won 6-4 6-4 in one hour and 36 minutes and will face Cori Gauff in the quarter-finals after she had another walkover against Johanna Konta.

Top seed Aryna Sabalenka had no such problems, cruising past Canadian Rebecca Marino 6-1 6-3 inside an hour.

Sabalenka sets up a quarter-final clash with fellow Belarussian and two-time Australian Open winner Victoria Azarenka.

Azarenka got past Greek 11th seed Maria Sakkari in three sets, 6-4 3-6 7-6 (7-2).

Fourth seed Karolina Pliskova got past Amanda Anisimova 6-1 7-6 (10-8) and will play Sara Sorribes Tormo in the last eight after she won in three sets over Katerina Siniakova.

Two-time Grand Slam winner Simona Halep's return to the WTA Tour ended in defeat to American Danielle Collins in almost three hours in the National Bank Open in Montreal on Wednesday.

World number 28 Collins triumphed 2-6 6-4 6-4 over the sixth seed Romanian, with the second-round match lasting two hours and 55 minutes.

Halep, who is a two-time winner in Montreal, was returning to the Tour for the first time in three months since suffering a calf tear against Angelique Kerber in Rome.

Collins, who has won titles recently in San Jose and Palermo, loomed as a tough first-up test for Halep, who broke twice to win the first set 6-2 as she generated eight break points to one.

The game turned from then on, as Collins sent down 4-1 aces in the second set and finished with 38 winners for the match.

Tokyo 2020 bronze medalist and third seed Elina Svitolina was bundled out in a second-round shock, losing 3-6 6-3 6-2 to Briton Johanna Konta.

Svitolina boasted a 5-0 record against Konta heading into the match but was beaten in a two-hour-and-11-minute struggle.

Top seed Aryna Sabalenka defeated former U.S. Open champion Sloane Stephens in three sets to secure her third-round spot.

Sabalenka fought back from the brink, rallying to win the last five games and triumph 7-6 (7-4) 4-6 6-4 over the American wildcard in a two hours and 25 minutes.

Fourth seed Karolina Pliskova came from behind to win 4-6 6-3 7-6 (7-2) over Donna Vekic, while Jessica Pegula also fought back after a slow start to topple 10th seed Anastasia Pavlyuchenkova 1-6 6-3 6-2.

Greek 11th seed Maria Sakkari won in three sets 6-4 6-7 6-4 over Veronika Kudermetova, while 13th seed Ons Jabeur responded after a lopsided first set to win 2-6 6-3 6-4 over Daria Kasatkina.

Cori Gauff progressed after being 5-0 up as Anastasia Potapova retired, while Amanda Anisimova, Camila Giorgi, Rebecca Marino and Sara Sorribes Tormo all won too.

Canadian local hope Marino will take on top seed Sabalenka, while Gauff faces Svitolina's conqueror Konta.