NEW YORK, NY, USA - Bianca Andreescu has seemingly celebrated a new milestone every time she steps on court, a phenomenon that entered warp speed at the US Open where the Canadian not only made her main draw debut, but secured her first Grand Slam second week, quarterfinal, and semifinal before surviving Belinda Bencic to book a scintillating championship clash with 23-time Grand Slam champion Serena Williams.

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Coach Sylvain Bruneau has enjoyed a front row seat to his pupil's wild success, but has also worked with the reigning BNP Paribas Open and Rogers Cup champion through the years of struggles that took the teenager to the pricipice of Grand Slam glory on which she stands.

"He's been with me through the ups and downs," noted the No.15 seed in her post-match press conference early Friday morning. "We've been working ever since the beginning of 2018, so we've been through a lot together."

It has how Andreescu has handled adversity - she was ranked as low as World No.243 last fall -that makes Bruneau believe she will acquit herself well in her maiden major final, regardless of the result.

"Tomorrow is a tough task," Bruneau admitted in his WTA Coaches press conference later that afternoon. "The toughest ask she's had this year in her young career, but she's a warrior and she's a street fighter. She strives to compete. I strongly hope and I'm pretty confident she's going to step in the arena tomorrow, both feet in, and going at it.

"Obviously there is another player on the court who is going to have her say in this match, but I'm pretty sure Bianca is going to be able to go and will go in there with the right frame of mind."

That other player happens to be a six-time US Open champion, one who navigated a tense opening salvo to her semifinal to steel past No.5 seed Elina Svitolina and reach her 10th final in Flushing Meadows.

Where Svitolina ultimately struggled beneath Williams' relentlessly brutal weight of shot, Bruneau calls Andreescu "the full package," one who can not only play and defense, but also employ her signature variety - not to mention her unwavering fighting spirit - to unsettle the former World No.1 on Saturday.

"If we look from an athletic standpoint, she's a great athlete. She's strong. She's fast. We see the way she covers the court. So she's got that going.

"Then you look at her mental aspect. She's as tough as it gets as a competitor. She's not scared. She goes for it. The bigger the occasion, the bigger she hits, and she does well. So she's got that, as well."

Though Andreescu trailed Bencic by a large margin in the second set of their semifinal, the Canadian star gave the Swiss fits as she roared back from a double break down, mixing up the pace on her forehand side to win the final five games of the match.

"Tomorrow is a tough task, the toughest ask she's had this year in her young career, but she's a warrior and she's a street fighter. She strives to compete. I strongly hope and I'm pretty confident she's going to step in the arena tomorrow, both feet in, and going at it."

- Sylvain Bruneau

"I'm a big, big fan of her game. I think she's got wonderful hands. She understands tennis. She sees the court. She understands the importance of doing different shots, not always the same shot over and over and over again."

Bruneau cultivated her tennis IQ out of a need to keep her intellectually stimulated in practice - observing a tendecy to tire of repetition - which created a player profile unlike any other presently on tour, and also gave Andreescu the courage to deviate from the metronomic style that has beecome the norm.

"I think it's just inside of me somehow," Andreescu said of her fearlessness. "I think it's just my passion for the game, as well. I don't like to lose, so I just try my best every match.

"I expect a lot from myself, so I think that pressure also helps me do my best in matches."

Andreescu will face a pressure unlike any other in the final, presenting Bruneau with a tough challenge of his own in order to prepare his pupil to play the biggest match of her life.

"It's not just another match, but we will try to pretend it's just another match, for sure. I think it's important for her to go in there the same way she's been going at it since the beginning of the year.

"If she goes there, competes, and believes in herself, and there is no reason that tomorrow it should be any different. Obviously she has a legend against her on the other side of the court, but that should not change what she has control over. I think that's going to be the message."

Andreescu takes on Williams on Arthur Ashe Stadium Saturday night.