It was as if Serena Williams was playing herself, the 17-year-old prodigy of 1999, when she won the first of her 23 grand slam titles, the first of six in front of her own fans – except the mirror answered back on Saturday night when the remarkable Bianca Andreescu, 19, won the title, beating her in straight sets.

It was her first slam final, the first time in four attempts she’d gone past the second round, and she became the first Canadian to win a major when, after an hour and 40 minutes that seemed much longer, she brought the drama to a close with a forehand into empty space that validated the 6-3, 7-5 scoreline.

Last year she couldn’t get out of qualifying in all four slams and finished the year ranked 178th in the world. When she leaves here, winning in her fourth appearance in a main draw, she will celebrate a remarkable season by breaking into the top ten.

In 11 seasons, 28-year-old Johanna Konta has beaten top-five players just seven times; since Andreescu joined the tour in 2015, she has beaten eight top-10 players in as many matches, and the results have come in a rush, interrupted by injury, over the past year.

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If, as many good judges suspect, this is the changing of the guard, it was a privilege to witness it. It was not a great match, but it was a significant one.

History almost weighed both of them down, but it was Andreescu, younger by nearly 19 years – the biggest age gap in a slam final in the Open era – who held steady. It was the grand dame of tennis who cracked, despite launching a brave and desperate fightback in the second set.

The very strangest look of the evening was ... the look of the 19-year-old winner. She stood alongside the 37-year-old loser (soon to be 38), as if she always expected to be receiving the plate, and there was no reason to be gobsmacked. This was her destiny. And she sounded as if she knew there would be more nights like this.

On court she was as composed as Buckingham Palace guard. Later, she cried – just like a little girl, as someone wrote – when she revealed she had seen it all unfolding long before the actual match. “It’s so crazy, man. I’ve been ... Sorry ... I’ve been dreaming of this moment for the longest time. A couple of months after I won the Orange Bowl [in 2015], I really believed that I could be at this stage. Since then, honestly I’ve been visualizing it almost every single day.”

For Williams, there was dignity and resignation – in pointed contrast to the horrible scenes of a year ago, when she mentally drowned in her own tears after an unwinnable verbal war with the chair umpire, Carlos Ramos (banished from her sight now), and the ice-cool handling of the crisis by her conqueror, Naomi Osaka.

Facebook Twitter Pinterest Andreescu after winning her championship point. Photograph: Justin Lane/EPA

Asked where she was at the time, Andreescu raised a laugh when she said, “I was at home. I was injured. I was sitting on my butt.” And, she admitted, she doesn’t think she watched it live.

Now the glare shifts irresistibly away from an established legend of the game to a player who has all the qualities to become one. She is added to the cast of prodigies in the women’s game being hailed as successors and saviours when Serena finally leaves the stage. They are stunningly impressive understudies, Osaka and Andreescu.

If anything, the Canadian has the edge. After Osaka won here and went on to add the Australian Open, she had bewildering dips and flights of fortune, complicated by injury, and repeatedly gave the impression she did not know what direction she was going in. She sacked her coach after winning two slams on the spin. That’s weird. But she is also delightful, and hugely talented. Theirs will be a rivalry to cherish.

Andreescu has capped a year that has also endured injury interruptions in the most spectacular fashion, the first Canadian to win a major.

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Now people are comparing her to Williams, who has ruled the game most of the time since she won her first slam here in 1999 and stands tantalisingly one short of the all-time record of 24 majors held by Margaret Court.

Andreescu sees the similarities – and the differences.

“We [both] like to keep the points short with our aggressive game style. We like to use our serve to our advantage. I think we fight really, really hard. But, at the same time I want to make a name for myself. I know I have a different game style to many players on the tour right now. It’s been working really, really well. It’s been working to my advantage. I just want to keep improving it.”

Williams sees it, too. “We’re really similar in that we both are fighters and we both are really intense. I feel like we both enjoy what we do, but at the same time – it’s hard to describe – super intense with what we do.”

Like Williams, Andreescu hits the ball with such power and certainty that opponents are mentally waiting for something impossible to handle. Her serve is big, but occasionally unreliable under pressure – as when she lost four games in a row in the second set. But she trusts her talent.

Facebook Twitter Pinterest Serena Williams congratulates Bianca Andreescu at the end of the match. Photograph: Adam Hunger/AP

Her attitude and demeanour in some matches has been volatile – but not here when it mattered most. There were no outbursts, not arguments, no reason to see she was reacting to pressure rather than creating it. She was doing what Williams has done for two decades when at the top of her game.

And, after losing four slam finals in her comeback after becoming a mother for the first time in 2017, Williams recognises that her dominance is not what it was. It would be remarkable if it were.

As she conceded later, “I felt like I could have done so many things a little bit better. But she played really well, and she deserves this championship. Today I thought she brought more intensity than versatility. I didn’t give her too much opportunity to have versatility. I love Bianca. I think she’s a great girl. But I think this was the worst match I’ve played all tournament.”

As for the Court record, Williams is trying her best to downplay the attention it has rightly attracted.

“I’m not necessarily chasing a record,” she said. “I’m just trying to win grand slams. It’s definitely frustrating. But, for the most part, I just am still here. I’m still doing what I can do.”

The game will miss her when she’s gone, an adornment to stubbornness, a proper queen of the court, regally brilliant at her best and most relaxed. It is her challenge to rediscover those qualities in the autumn of her career.