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.

Casper Ruud continued his excellent winning streak while Stefanos Tsitsipas made it a birthday to remember at the National Bank Open in Toronto.

Tsitsipas turned 23 on Thursday and marked the occasion with a 6-3 6-2 win over Karen Khachanov.

The Greek star was presented with a cake by tournament officials after his win, as the crowd serenaded him with a chant of 'happy birthday'.

It marks a significant improvement on when Tsitsipas turned 20. On that occasion, he lost the 2018 final of this event to Rafael Nadal.

Next up for Tsitsipas is Casper Ruud, who poked fun at his critics after he eased into the quarter-finals.

Ruud, the world number 12, won three titles on clay courts in July and has now continued that form in the ATP Masters 1000 event.

Playing on a hard court has proved no challenge for the in-form Norwegian, who wrote 'Hard Courts' with a smile underneath on the camera after his 6-4 6-3 victory over Dusan Lajovic on Thursday.

"I have seen a lot of people questioning my ability to play on hard court, so I just thought it was funny to write a little note," Ruud said in a news conference.

"I think it's fun to play on hard courts. Even though I (have achieved) most of my best results on clay, my best slam result is from this year’s Australian Open (where he reached the Round of 16), so I think it's a surface that also can suit my game well even though this year has been mainly clay.

“I think I'm motivated to come back to the hard courts. I have had two very good matches here. It's a great start for me to the hard-court swing."

Ruud, in the hunt for his fifth title of 2021, has won the only previous meeting between the duo.

"[I am] looking forward to that battle," Tsitsipas said. "We have played each other in the past. Not an easy guy to play against. Looking for a change, looking for a switch-up this time."

However, there was no place in the last eight for world number seven - and Olympic gold medallist - Andrey Rublev, who went down 7-5 7-6 (7-5) to American John Isner.

Fresh from a triumph in Atlanta, 36-year-old Isner has looked sharp all week and has now won eight successive matches.

It brings up a third quarter-final appearance for the world number 30 in Canada, and he will play French 11th seed Gael Monfils after he got past lucky loser Francis Tiafoe 6-1 7-6 (7-2). Monfils will be competing in his first ATP Tour quarter-final in 18 months.

Top seed Daniil Medvedev proved too good for Australian qualifier James Duckworth, winning 6-2 6-4 in one hour and eight minutes.

Medvedev was in ominous form on the hard court, sending down 10-1 aces and winning 27 of 32 points on his first serve.

The Russian world number two will play seventh seed Hubert Hurkacz who fought back to win 6-7 (7-9) 6-4 6-4 over Nicolas Basilashvili.

Eighth seed Diego Schwartzman lost in three sets to 10th seed Roberto Bautista Agut after the Spaniard saved three match points.

Bautista Agut will next play Reilly Opelka who came from behind, and also saved a match point, to win over Lloyd Harris in three.

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.

Canadian fifth seed Denis Shapovalov was a major casualty in the second round of the National Bank Open in Toronto after a straight-sets defeat to Francis Tiafoe.

Unseeded American Tiafoe swept aside the local 6-1 6-4 in one hour and 15 minutes to secure his third-round spot against 11th seed Gael Monfils who beat John Millman 3-6 6-3 6-4.

Tiafoe was only in the Toronto main draw as a lucky loser after being defeated in qualifying by Emil Ruusuvuori but he hit 14 winners in an emphatic display.

World number 10 Shapovalov was unable to generate any break points while Tiafoe reeled off five games in a row, with two breaks, to win the first set.

The Canadian continued to struggle with his serve in windy conditions, as the American world number 52 won 88 per cent (23/26) of points on his first serve.

Another local hope, ninth seed Felix Auger-Aliassime, also was eliminated, going down 7-5 6-4 to Serbian Dusan Lajovic.

The Canadian hit six aces to Lajovic's none, but was undone by unforced errors at key times, with a double fault gifting the Serbian a 6-5 lead in the opening set.

Australian 12th seed Alex de Minaur also bowed out after a one-sided 6-1 6-1 defeat to Georgian world number 42 Nicolas Basilashvili.

Basilashvili sent down 6-2 aces and converted five of his six break points generated in an impressive display.

Australian qualifier Jack Duckworth booked a third-round ticket against top seed Daniil Medvedev after upsetting 16th seed Jannik Sinner, who won last week's Citi Open.

Fourth seed Andrey Rublev won through with a 7-6 (7-4) 6-3 victory over Fabio Fognini, while seventh seed Hubert Hurkacz progressed with a walkover after Kei Nishikori retired with a shoulder injury.

Eighth seed Diego Schwartzman beat Benoit Paire 7-5 6-1, while 10th seed Roberto Bautista Agut handled Tommy Paul 6-3 6-4.

John Isner knocked out 13th seed Cristian Garin in three sets, while Lloyd Harris beat Feliciano Lopez in two and Karen Khachanov defeated compatriot Aslan Karatsev 7-6 (9-7) 6-4 to secure a third-round meeting with third seed Stefanos Tsitsipas.

Tsitsipas pledged to help those affected by the fires in his homeland in his post-match press conference on Tuesday.

“My heart is with all the people of Greece,” Tsitsipas said. “I come from the south suburbs of Athens. When I was there a few days ago, I could see the fires from the south. Huge, giant clouds, smoke, which you could see from far, far away. It wasn't very nice. Even at the beach that day when I went to swim, you could see all the debris from the smoke and from the fires in the sea.”

Daniil Medvedev and Stefanos Tsitsipas survived three-set scares at the National Bank Open on Tuesday, but five-time tournament champion Rafael Nadal departed Toronto without even taking the court. 

Top seed Medvedev, who won just three games against Nadal in the final in 2019, the last time the tournament was played, prevailed 4-6 6-3 6-4 in his opener against Alexander Bublik.

The man Nadal beat to win the title the previous year, Tsitsipas, failed to convert on five match points in an epic second-set tiebreak but recovered to down Ugo Humbert 6-3 6-7 (13-15) 6-1.

Nadal pulled out ahead of a scheduled match against Lloyd Harris, who beat him last week in Washington as the 20-time grand slam winner struggled with a foot injury. 

Countryman Feliciano Lopez replaces Nadal in the draw and will face Harris on Wednesday. 

Elsewhere Tuesday, sixth seed Casper Ruud needed more than two hours to put away Marin Cilic 6-3 3-6 6-3, while 14th seed Grigor Dimitrov suffered a quick 6-3 6-4 exit against big-serving American Reilly Opelka.

A pair of unseeded veterans advanced, with 2016 finalist Kei Nishikori a 6-4 6-7 (5-7) 6-2 winner over Miomir Kecmanovic and John Isner defeating Alejandro Davidovich Fokini 6-4 6-1 in just over an hour.

Two days after appearing in his first ATP Tour final at the Citi Open, Mackenzie McDonald fell 6-3 6-4 to Benoit Paire in his Toronto opener. 

In other first-round matches, Karen Khachanov beat Cameron Norrie 6-4 5-7 6-4, Frances Tiafoe downed Yoshihito Nishioka 6-4 6-3, Dusan Lajovic handled Emil Ruusuvuori 3-6 6-3 6-3 and Nikoloz Basilashvili defeated Jenson Brooksby 2-6 6-0 6-4.

Rafael Nadal has withdrawn from the National Bank Open ahead of his opening match due to a left foot injury.

The Spaniard made a return to action on the ATP Tour last week at the Citi Open, his first outing since suffering defeat to Novak Djokovic in the semi-finals of the French Open in June.

His comeback was aimed at getting prepared for the US Open but, having lost in the last 16 in Washington to Lloyd Harris, he will not now be participating in Toronto.

"I really wanted to play here a lot, but now is the moment to make a decision, and this is unfortunately the decision that I have taken," Nadal told the media.

"I have had this issue for a couple of months, as people know.

"Of course, it is not a happy situation after all the success that I had here in Canada, not being able to play this year after missing a year. It's a tough one, but that's how it is today."

Nadal skipped Wimbledon citing the need to recover after the clay season, while the left-hander also opted out of representing his country at the Tokyo Olympics.

The five-time champion in Toronto was scheduled for a repeat meeting with Harris in the second round. Instead, his place in the draw goes to compatriot Feliciano Lopez.

South African Lloyd Harris booked a second-round date with Rafael Nadal at the National Bank Open after a straight-sets win over Canadian qualifier Brayden Schnur on Monday.

World number 49 Harris eased past Ontario-born Schnur 6-3 6-2 in one hour and 17 minutes in Toronto.

Harris sent down nine aces, winning 78 per cent of points on his first serve, converting four from four break points on return.

Nadal is a five-time champion in Toronto, winning the previous two editions in 2018 and 2019.

Marin Cilic, who won his first title for three years in Stuttgart, beat Albert Ramos-Vinolas 6-2 4-6 6-3 in two hours and 13 minutes.

The 32-year-old will face sixth seed Casper Ruud in the next round.

Fabio Fognini also needed three sets to progress, battling from behind to defeat Jan-Lennard Struff 6-7 (2-7) 6-2 6-4 to set up a meeting with Andrey Rublev.

Ugo Humbert impressed in his straight-sets defeat of Lorenzo Sonego and will next face third seed Stefanos Tsitsipas, while qualifier James Duckworth beat Taylor Fritz to secure a showdown with Citi Open winner Jannik Sinner.

Alexander Bublik defeated Briton Dan Evans in straight sets to earn a second round meeting with top seed Daniil Medvedev, while Australian John Millman will face 11th seed Gael Monfils after beating Ricardas Berankis.

Reilly Opelka came from a set down to win over Australian Nick Kyrgios, while Tommy Paul also fought back to beat Canadian Vasek Pospisil.

Karolina Muchova was a casualty in the first round of the National Bank Open as she was stunned by Oceane Dodin in Montreal on Monday.

The 14th seed was undone by the French qualifier despite Dodin sending down 10 double faults.

The 6-3 1-6 6-2 success was Dodin's first over a top-25 player this season.

Former U.S. Open finalists and 16th seed Madison Keys was also a first-round casualty, going down 6-3 6-3 to Canadian Rebecca Marino.

Toronto-born Marino, currently ranked 220th in the world, won in one hour and six minutes, converting four of her eight break points, while she saved four from five too.

However, there were no such problems for Ons Jabeur, the 13th seed strolling to a 6-1 6-3 victory over Clara Burel.

Eleventh seed Maria Sakkari also had a routine day, her opponent Marie Bouzkova unable to continue with Sakkari ahead 6-4 3-1.

An Olympic gold medallist in the doubles at Tokyo 2020, Katerina Siniakova had more to celebrate in the singles with a 6-1 6-3 win over long-time rival Jelena Ostapenko.

Elsewhere in the draw, Paula Badosa, Sorana Cirstea, Amanda Anisimova, Nadia Podoroska and Fiona Ferro all progressed.

Novak Djokovic will not play at the Western and Southern Open after a "taxing" run that has brought him to the brink of a calendar Grand Slam.

The world number one's bid for a Golden Slam faltered at the Olympic Games as he lost to Alexander Zverev in the semi-finals in Tokyo.

Djokovic appeared to tire badly and finished fourth in both the men's singles event and the mixed doubles, opting out of the bronze medal match in the latter.

But victories at the Australian Open, French Open and Wimbledon mean 2021 is still on course to be the best year of Djokovic's career.

And the Serbian is taking a little time to prepare himself for the final push at Flushing Meadows, meaning no appearance in Cincinnati next week.

"Dear fans," he wrote on Twitter. "I wanted to share with you that I am taking a bit longer to recover and recuperate after quite a taxing journey from Australia to Tokyo.

"Sadly, that means I won’t be ready to compete in Cincinnati this year, so I'll turn my focus and attention to the US Open and spend some more time with family.

"See you in New York soon!"

Former world number one Andy Murray has been handed a place in the main draw of the US Open after Stanislas Wawrinka pulled out.

Murray, the 2012 champion at Flushing Meadows, reached the second round of the event last year, which was won by Dominic Thiem.

The 34-year-old, who competed in the men's doubles at the Tokyo Olympics, has only played eight Tour-level matches in 2021. He was handed a wildcard for Wimbledon, where he lost in the third round to Denis Shapovalov.

Novak Djokovic is due to lead a strong men's field for the tournament in August, which will be played in front of capacity crowds.

The world number one is seeking to become the first man to win all four major championships in the same year since Rod Laver in 1969.

Rafael Nadal and Roger Federer, who are tied with Djokovic on 20 grand slam singles titles, are also set to play.

Wawrinka, himself a champion in New York in 2016, is still recovering from his second foot surgery of the year.

With summer's main events about to begin, no one on the WTA tour is hotter than Danielle Collins. 

Two weeks after winning her maiden title in Palermo, Collins claimed the Silicon Valley Classic crown in San Jose, California by defeating Daria Kasatkina 6-3 6-7 (10-12) 6-1 on Sunday.

It was the 10th successive match victory for the American, who is ranked 36th in the world and poised to move up as the hard-court season intensifies with WTA 1000 events at Montreal and Cincinnati ahead of the U.S. Open. 

While it appeared for a while that Collins would cruise to another easy win, Kasatkina made it a fight in the 73-minute second set. 

The Russian had prevailed in the two previous meetings between the players, and she saved two championship points down 4-5 in the second and three more in winning the tiebreak. 

That marked only the second set Collins has dropped during her 10-match run, the other coming against Sloane Stephens in the second round earlier this week. 

Kasatkina's momentum was short-lived, however, as Collins broke her serve early in the third and never looked back.

Before her clay-court title run at Palermo, Collins had been 0-6 in semi-finals in her career. 

Italian teenager Jannik Sinner has claimed his third career ATP Tour title with a three-set victory over Mackenzie McDonald in the Citi Open final on Sunday.

The sixth seed triumphed in two hours and 52 minutes, winning 7-5 4-6 7-5 over the unseeded American, who was competing in his first ATP Tour final.

The Washington, D.C. victory was 19-year-old Sinner's first ATP 500 title and his third on tour, having triumphed in Sofia late last year and Melbourne earlier this year.

Home favourite McDonald put plenty of pressure on Sinner, forcing the Italian to save seven break points for the match.

McDonald also staved off 16 break points in an enthralling contest where the Italian sent down nine aces to the American's five.

Sinner lost his serve twice in the opening set and needed 11 set points but still won 7-5, before the American hit back, dropping further behind the baseline to good effect in the second, levelling it with a 6-4 win.

The Italian claimed an early break in the last to open up a 3-0 lead, before failing to convert two championship points at 5-2.

McDonald brought it back to 5-5, with numerous dramatic rallies throughout, before the 2019 Next Gen ATP Finals champion broke in the 12th game to triumph in the third set.

Andrea Petkovic claimed her first singles title on the WTA Tour in over six years thanks to an emphatic victory over Mayar Sherif at the Winners Open.

Petkovic was far too strong for her Egyptian opponent in Sunday's final, easing to a 6-1 6-1 triumph after just over an hour on court in Cluj-Napoca.

The impressive result sealed the German a seventh tournament win in her career, though she had not reigned at an event since her success in Antwerp back in February 2015.

Sherif had become the first Egyptian to reach a singles final on the WTA Tour and received praise from her opponent during the presentation ceremony.

"This has been a great week, but not only that, what's really important is you're paving the ground for all the girls in a part of the world which doesn't appreciate tennis as much as we do here in Europe," Petkovic said to the 25-year-old.

"It's so much more important than winning every title every week, though I'm sure you will get there as well. 

"Just being out there competing, being the first Egyptian woman to make a WTA final, to break into the top 100, I think that's incredible. I want to congratulate you on that – keep going."

Petkovic raced into a 5-0 lead in the opening set before Sherif held serve; she also survived two break points to move ahead at the start of the second.

However, the second seed reeled off the next six games in a row, clinching the result with a forehand winner.