"Isn't that the young Canadian tennis star?" a fan wondered aloud standing near practice court No. 1 at the USTA Billie Jean King National Tennis Center in New York Thursday night.

"That's her. That's Bianca. She's going to be a champion," another fan nearby chimed in.

Bianca Andreescu's meteoric rise in the tennis world over the past season is nothing short of remarkable, and fans at the U.S Open can't get enough of the 19-year-old from Mississauga, Ont.

Just a couple of hours before her Thursday night semifinal victory over Belinda Bencic, Andreescu left the practice court and was bombarded by fans waiting for an autograph or photo with her — she stopped for nearly every one.

It was as if Andreescu had done this so many times before, soaking up the spotlight while remaining poised and humble as she thanked fans for their support.

WATCH | CBC's Greg Ross with Bianca Andreescu

CBC News' Greg Ross caught up with Bianca Andreescu, ahead of Saturday's U.S. Open final against Serena Williams. 3:55

You'd never know this is Andreescu's U.S. Open debut and she's now the first Canadian singles player — male or female — ever to make it into the championship match in New York.

"It's just crazy what a year can do," Andreescu said. "I've dreamt of this moment ever since I was a little kid. But I don't think many people would have actually thought that it would become a reality."

She finished last season ranked 178th. Andreescu will be in the top 10 by next week.

Born in Canada, Andreescu moved to her parents' home country of Romania at seven years old. That's where she started playing tennis for the first time. The family moved back to Mississauga, where she joined the national team.

Ever since, she's been on a mission to get to this point in her tennis career. In fact, after her thrilling come-from-behind, second-set victory on Thursday night, Andreescu revealed she'd been visualizing playing in the U.S. Open final for years.

WATCH | Andreescu vs. Williams: Tale of the tape

Canadian 19-year-old Bianca Andreescu wasn't even born when Serena Williams won her first US Open title. Now, the two will vie for the tennis major with Williams looking to tie the record with 24 major titles, while Andreescu will look for her first ever. 1:32

"When I was 16, after I won the Orange Bowl title, I remember I wrote myself a cheque of this tournament — winning it, obviously," Andreescu said. "Ever since that moment, I just kept visualizing that. If that can happen on Saturday, then that would be pretty cool."

She still has the cheque to remind herself of the goal.

There's a thin line in high-performance sport separating the champions from the rest — it's in the most pressure-packed moments elite athletes have defined their destiny and cemented themselves in history.

And in just a short amount of time Andreescu has shown an ability to rise up to every challenge. She's won 12 consecutive three-set matches and is 44-4 this year, the best record on the tour.

The bigger the pressure, the higher the stakes, the more dramatic the moment, the better Andreescu is.

WATCH | Highlights from Andreescu's semifinal win

Bianca Andreescu beat Belinda Bencic 7-6(3), 7-5 to advance to her 1st career Grand Slam final. The U.S. Open final will be a rematch of last month's Rogers Cup final in which Andreescu won after Serena Williams retired. 2:22

"I think it's just inside of me somehow. I think it's my passion for the game. I don't like to lose," she said. "I think when I'm down I play my best tennis. Whenever my back is against the wall, I think I'm just extra focused in those moments."

Her coach agrees. Sylvain Bruneau points to her stunning comeback in the second set of the semifinal, winning five straight games, to highlight her never-give-up nature.

"She's a warrior. She's a street fighter. She loves competing," Bruneau said. "I think that's part of her signature, that's part of her DNA as a player. She never gives up — but only she's able to do that. She comes up with something special at very key moments."

Andreescu's coach, Sylvain Bruneau, says the teen is a warrior on the court, and her will to compete is 'part of her DNA.' (Julian Finney/Getty Images)

Standing in the way of Andreescu's historic pursuit at the U.S. Open is one of the best players in history.

Serena Williams' list of achievements, specifically at the New York Grand Slam, is staggering.

She'll be making her 33rd Grand Slam final appearance overall and her 10th at the U.S. Open. Williams has 23 Slam titles, one away from tying Margaret Court for the most ever. Should she win, she'll also become the career leader for most singles wins at the U.S. Open, with 102. It would also mark Williams' seventh championship win at Flushing Meadows.

Perhaps most remarkable is that Williams is back in the U.S. Open final 20 years after she won her first title — she was 17 years old in 1999 when she first won it all.

"At 17, I thought for sure I'd be retired at 28, 29, living my life. I would have thought it was a sick joke," Williams responded when asked about being back in the final.

Andreescu hadn't even been born.

"I've wanted to play her. I remember telling my team I would have always wanted to play her right before she retires," Andreescu said. "I'm really looking forward to it. She's an amazing champion on and off the court."

It was only last month the two met for the first time on the court — that short-lived Rogers Cup final in Toronto in which Williams retired from the match just four games in because of an injury.

Nobody will ever forget the light-hearted, tear-filled moment between the two on the court after the match was called. Andreescu and Williams hugged, cried and laughed together.

WATCH | Andreescu consoled Williams after tennis icon retired from Rogers Cup final

Bianca Andreescu and Serena Williams shared an emotional embrace after Williams was forced to retire from the Rogers Cup final due to injury. Andreescu is the first Canadian woman to win the Rogers Cup since Faye Urban in 1969. 2:14

Afterward Williams called the Canadian teen an "old soul" because of her kindness, compassion and caring.

"I just like her as a person. She's amazing," Williams said.

Though they are at the opposite ends of their careers, the two have immense respect for one another.

"I always say that if I can do it, if Serena can do it, anyone can do it. For me to get where I am now, a lot of other Canadians paved the way, so hopefully I can do that for others," Andreescu said.

Andreescu is trying to secure her first Slam title. Williams is trying to add another to her long list. It'll be a historic U.S. Open final no matter the outcome.