Canadian teenager Leylah Fernandez shocked US Open second seed Aryna Sabalenka 7-6 (7-3) 4-6 6-4 to reach her first grand slam final on Thursday.

Fernandez continued her giant-slaying run at Flushing Meadows, where the 19-year-old sensation has stunned defending champion Naomi Osaka, 2016 winner Angelique Kerber, fifth seed Elina Svitolina and Sabalenka en route to the decider.

Fellow teenage sensation Emma Raducanu or 17th seed Maria Sakkari await Fernandez in Saturday's final in New York.

The defeat is a bitter blow for Belarusian star Sabalenka, who has never reached a major final, having also lost in the final four at Wimbledon this year.

The semi-final was full of momentum swings, but 52-23 unforced errors and 8-2 double faults ultimately were costly for Sabalenka, who lost the final game on her serve to love to hand Fernandez victory.

Sabalenka had raced to an early 3-0 lead inside 10 minutes on Arthur Ashe Stadium, dominating with her power, missing only one of her first 13 first serves, before Fernandez settled into the contest.

Trailing 4-2, Fernandez – the youngest woman to beat multiple top-five opponents at the same slam since Serena Williams in 1999 – broke back as Sabalenka's first serve let her down, with the former converting the third of three break points.

Fernandez, who survived a break point to level it up at 4-4, eventually closed out the first set in a tie-break.

Sabalenka made a statement by breaking to love in the opening game of the second set, but Fernandez responded with a break of her own to level it at 2-2.

The second seemed destined for another tie-break, however Sabalenka broke to lead 5-4 and she never looked back as the 23-year-old forced a deciding set.

Fernandez seized control, breaking Sabalenka to move 4-2 ahead, though the latter responded immediately, despite the teenager taking her service game to deuce after trailing 0-40.

However, Fernandez held serve at 5-4 before breaking Sabalenka again to love to claim another memorable victory at the US Open.

Data Slam: Oh, Canada!

Fernandez's victory marks the second time in three years that a Canadian teenager has reached the US Open final, with then-19-year-old Bianca Andreescu beating Serena Williams in 2019. Canadian Felix Auger-Aliassime remains alive in the men's semi-finals too.

WINNERS/UNFORCED ERRORS

Fernandez – 26/23
Sabalenka – 45/52

ACES/DOUBLE FAULTS

Fernandez – 6/2
Sabalenka – 10/8

BREAK POINTS WON

Fernandez – 4/7
Sabalenka – 4/11

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

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.

Aryna Sabalenka won the Madrid Open after a 6-0 3-6 6-4 victory over world number one Ashleigh Barty on Saturday.

Sabalenka wrapped up the first set to love in just 25 minutes as an unusually sluggish Barty struggled to find any kind of rhythm to her game.

Barty, who had won 16 consecutive matches on red clay, rallied in the second set to get herself back on level terms.

At 4-4 in the deciding set Sabalenka broke Barty and then held her nerve on serve to secure her 10th WTA Tour career title which will see her climb up to fourth from seventh in the world rankings on Monday.

Barty was on a streak of nine consecutive WTA Tour titles and had not lost to an opponent in the top 10 since the WTA Finals in 2019.

But in-form Sabalenka had not dropped a single set in Madrid in the lead-up to the final and began in imperious fashion.

The 23-year-old from Belarus produced a clinical first set, dropping just four points, as Barty failed to win a single game in the set to record a bagel for the first time in four years.

The pair exchanged breaks in the second set before Australian Barty, 25, finally discovered some momentum to break her opponent again to seal the set.

Sabalenka squandered a one-set lead to lose to Barty in the Stuttgart Open final two weeks ago.

And Barty, also playing in the final of the tournament for the first time, had threatened to break her opponent at 4-3 in the decider.

But this time Sabalenka took her chance when Barty fluffed a drop shot and then double faulted to give her three break points, converting at the first time of asking with a powerful backhand.

Sabalenka then clinically sealed victory with a flawless service game to love, clinching victory when Barty smashed a forehand into the net.

"To be honest, after the final in Stuttgart I was injured, I couldn't move and wanted to withdraw," Sabalenka said in an on-court interview after the win.

"But the recovery was good, in four days I feel better and now I'm the champion. It's been an amazing week."