Bianca Andreescu ready for her defining moment vs. Serena Williams in US Open final

Andreescu takes down Bencic to advance to finals (0:32)

Bianca Andreescu eliminates Belinda Bencic in straight sets to advance to the US Open final against Serena Williams. (0:32)

NEW YORK -- After dropping the first set of her first Grand Slam quarterfinal to Elise Mertens in lifeless, error-ridden fashion, Bianca Andreescu walked to her chair at Arthur Ashe Stadium, her frustration seemingly dripping off her like sweat.

She sat in her chair, rummaged through her bag to find a dry shirt and tried to motivate herself before taking the court again.

What exactly did she say to herself?

"Get your s--- together," the 19-year old remembered later in front of a delighted crowd.

And her pep talk worked. Andreescu stormed back from 3-6 to win the next two sets convincingly, 6-2, 6-3, in just over two hours in total to advance to Thursday's semifinals. She had 40 winners on the night, and won 82% of her net points -- including eight of nine in the third set. She clinched the victory with a backhand winner and put her hands on her head in disbelief. She then shook her fists as she turned to look at her family and friends in her player box. "Is this real life?" she mouthed to them twice.

If Andreescu was shocked Wednesday, it was nothing compared to how she felt Thursday after she punched her ticket to her first major final behind a 7-6 (3), 7-5 win over Belinda Bencic. Down 5-2 in the second set, she pulled off yet another dramatic comeback behind another 40 winners and a strong first serve. She put hands on her head in victory for the second straight night, and kept repeating, "Oh, my God" to herself.

After shaking Bencic's hand, she ran back onto the court, jumped up and down and raised her arms to pump up the crowd. "Come on!" she yelled twice to the fans, before saying it softly to herself one more time.

"I've always dreamt of this moment ever since I was a little kid," she said in the early-morning hours Friday. "But I don't think many people would have actually thought that it would become a reality."

No one can blame her for her reaction. Her run to the final would be impressive for anyone, but it's particularly noteworthy because this is her first appearance at the US Open and only her fourth main draw appearance at a Grand Slam. It marked her 12th consecutive victory as she became the first Canadian woman to reach the title match in New York.

"I don't think anyone [is] surprised," said Bencic when asked if Andreescu's run to the final was unexpected. "Honestly, she won Indian Wells, Toronto. She beat so many great players. I definitely was not surprised. I don't think anyone should be.

"I think she's definitely a great player. She totally deserves to be in the final."

With a big game and a personality to match, Andreescu, 19, has quickly become a fan favorite in New York, and on tour. She counts two-time NBA MVP Steve Nash and New York Liberty star Kia Nurse among her growing legion of fans. She has the athleticism and swagger of a basketball player, and the confidence of someone far more accomplished. But she's getting there quickly.

To say the Canadian has had a breakthrough year would be an understatement. She opened 2019 by qualifying at Auckland, then made an unexpected run to the final, upsetting top seed Caroline Wozniacki along the way. As a wild card at Indian Wells -- her first premier tournament -- she stunned the field, fans and the media alike with a dominant performance, which included wins over Garbine Muguruza, Elina Svitolina and Angelique Kerber, to take home the title.

"The fricking champion of Indian Wells," said Andreescu, then 18, shortly after becoming the youngest champion at the event since Serena Williams in 1999, and the first wild card to do so. "It's crazy."

She was sidelined for much of the summer because of a right shoulder injury, but in front of a supportive home crowd at the Canadian Open in Toronto, the Ontario native won her first tournament back after more than two months away and became the first Canadian woman to do so since 1969. She was leading Williams 3-1 in the first set of the title match before the 23-time Grand Slam champion retired because of a back injury. Their on-court conversation quickly went viral, as Andreescu tried to console a crying Williams.

"I'm so sorry," Andreescu said before asking if she could give Williams a hug. "I've watched you your whole career, you're a f---ing beast. Injuries -- I've been through so many already, and you know how they are. This sucks -- on your back, right? I know everything about you!"

"I'm officially a fan," Williams said later. "I mean I was before, but I was really sad, and she made me feel a lot better, so that was really nice. She's only 19, she definitely doesn't seem like she's a 19-year-old in her words on court, her game, her attitude, her actions."

Added Williams after her own semifinal win Thursday: "She really knows how to mix up the game and play different shots in different ways. Above all, I just like her as a person. She's amazing."

Born in Canada to parents who had emigrated from Romania in 1995, Andreescu moved with her parents to their native country when she was 7. It was there she first picked up a tennis racket, but she didn't get serious about the game until the family returned to the Toronto area a few years later.

Andreescu's mother, Maria, who was wearing her signature sunglasses and a colorful shirt that read "Dog Queen" on the collar while holding Bianca's dog, Coco, on her lap for most of the quarterfinal Wednesday, has become a social media sensation in her own right throughout the tournament, which only helps her daughter's budding popularity. Bianca says her mother is her lifelong role model and the reason for her confidence. "My mom's honestly the coolest person I know," she said after Wednesday's match.

Andreescu hasn't lost a match since the second round of the French Open in May. Based on her strong performance in Queens, which includes wins over Wozniacki and Taylor Townsend, it seems as if maybe she has forgotten what it's like to lose, and doesn't want to remember.

"I'm just fighting really hard," Andreescu said. "It's not over 'til it's over. I have had many situations where I have come back from 5-0 down and won the match, and even vice versa. ... You never really know, so I just try to play every point like it's the last."

Andreescu and Williams have a rematch in the final Saturday in what would be their second career meeting. With an 18-year age difference between the two, it marks the largest age gap in a final in the history of the Open era. To wit, Williams had already won a US Open title before Andreescu was born.

If that weren't enough to evidence the generational divide between the two players, Andreescu is the first player -- including men -- born in the 2000s to reach a major final.

Though Williams is still very much a contender at every tournament she plays, Andreescu is cementing her spot in a crop of exciting young players that includes Coco Gauff and Caty McNally, as well as slightly older stars such as Naomi Osaka and Ashleigh Barty. If Andreescu can win Saturday's final, she will be very much part of the present, as well as the future.

As a 15-year-old, she wrote a check to herself in the amount of the US Open prize money. She still has it, and has visualized it regularly, although she wouldn't mind replacing it with a real one.

But none of this has fully sunk in yet. Currently ranked No. 15, she will break into the top 10 for the first time next week regardless of how she fares from this point. And no matter what, she's happy to have gotten this far. It's a far cry from losing in the first round of qualifying, as she did here last year.

Asked what she would have said to someone who told her where she would be this year, she laughed.

"I don't think I would have believed them," she said. "I was ranked, like, outside of the 150, I think. It's just crazy what a year can do.

"I remember always telling my team I would have always wanted to play [Williams] right before she retires. I'm really looking forward to it. She's an amazing champion on and off the court. It's going to be fun.

"I'm sure she's going to bring her A-game. I'm going to try to bring my A-game, too. Hopefully, I guess, may the best player win."