As players walk out of the the tunnel and into Arthur Ashe Stadium, they are greeted by a plaque adorned with four famous words uttered by Billie Jean King - "Pressure is a privilege".

Of all the greats to have graced the sport of tennis, no player has embraced that motto more than Serena Williams.

At her most dangerous with her back against the wall, Williams' major-trophy laden career has been defined by the American's ability to thrive when the match situation appears most dire, to ratchet up the intensity and summon her very best when it is most needed.

However, standing between her and a record-tying 24th grand slam title in the US Open final is a teenager who may be her heir apparent in that regard.

Bianca Andreescu only has eight major match wins to her name, six of them coming in this year's event at Flushing Meadows. She was not even born when Williams appeared in her first slam final.

The contrast between the two finalists could not be more stark. Yet, when it comes to on-court intensity, there is a strong argument that Andreescu is already the 37-year-old's equal.

If she continues to produce turnarounds akin to her second-set comeback in the semi-final with Belinda Bencic, the Canadian will soon have a similar reputation for excelling in the moments the vast majority shrink under.

Aptly described as a "warrior and a street fighter" by her coach Sylvain Bruneau on Friday, at the age of 19 Andreescu is a wonderfully entertaining player to watch.

She is blessed with great power and brings tremendous variety to her game, but it is what she does after and in-between points that makes so mesmeric.

Andreescu lives and breathes for every point. In each game she seems to fight with her own internal sense of frustation and it is a surprise when a point she wins is not greeted by a vociferous "Yes! C'mon!" or by her barking at her support team.

Comfort is not a word that naturally comes to mind when watching Andreescu. However, she seems most at ease when in need of a fightback, so being break-point down is viewed more as an opportunity rather than a problem.

Trailing 5-2 in the second against Bencic, having won the first on a tie-break, there was never any thought of her easing off and saving energy for a decider. Andreescu attacked, Bencic got tight and any confidence the Swiss had built up ebbed away as she lost five straight games and handed the match to the main-draw debutant.

"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," Andreescu told a news conference.

"I remember I told myself at 5-2 that I didn't want to go in three sets. So I think just that switched my mindset. I was just really, really focused.

"It's [fearlessness] just inside of me somehow. 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's belief has grown throughout a stunning year. Having failed to qualify for the US Open last year, her 2019 has encompassed a final in Auckland and titles at Indian Wells and the Rogers Cup, where an ailing Williams retired four games into the final.

The desire to win at Flushing Meadows, however, has been there for a long time.

"When I was 16, after I won the Orange Bowl title, I remember I wrote myself a cheque of this tournament, winning the tournament obviously," said Andreescu. "Ever since that moment, I just kept visualising that.

"If that can happen on Saturday, then that would be pretty cool."

She will be able to cash a cheque for $3.85million should she prevail on Saturday. To do so, Andreescu will need to overcome the greatest player of all time, with Williams chasing history in front of her home crowd at the world's biggest tennis stadium.

A monumental challenge, but one Andreescu will unquestionably show no fear in facing.