NEW YORK — Already regarded as the greatest women's player ever to pick up a tennis racquet, Serena Williams's legacy is already assured but the record equaling 24th Grand Slam that would help build statistical proof remains frustratingly out of reach.

Twenty years ago a 17-year-old Williams walked away from the US Open with what would be the first of her 23 Grand Slam titles. On Saturday she had the chance to equal Margaret Court's all-time record but instead it was Canadian teenager Bianca Andreescu grabbing the trophy with a 6-3, 7-5 win.

That victory not only raised questions about whether Williams would ever get beyond 23 Grand Slam titles, many also viewed 19-year-old Andreescu's win as a changing of the guard in women's tennis.

Since giving birth to her daughter in 2017, Williams has not won a tournament.

Four times now, twice at Wimbledon (2018, 2019) and at the US Open (2018, 2019) Williams has come agonizingly close to that 24th Grand Slam only to fall at the final hurdle.

She did not just lose all four finals – she failed to win a single set.

The next time Williams can attempt to equal Court's record at the Australian Open in January she would be 38, the climb to the summit ever steeper.

But a defiant Williams refused to accept there would not be another Grand Slam in her future.

"All of it honestly, truly is super frustrating," said Williams. "I'm, like, so close, so close, so close, yet so far away.

"I don't know what to say. I guess I got to keep going if I want to be a professional tennis player.

"And I just got to just keep fighting through it.

"I'm not necessarily chasing a record. I'm just trying to win Grand Slams.

"It's definitely frustrating. I'm still doing what I can do."

Like Tiger Woods and Michael Jordan, Williams is an athlete who moves the needle. What she wears, eats and says matters. In the Big Apple, where there is no shortage of distractions for A-listers on a Saturday afternoon, it was the Serena Williams show that was the hot ticket.

When the Queen of Tennis holds court in New York it attracts sporting royalty and on occasion the real thing. Williams's good friend Meghan Markle, the Duchess of Sussex, was cheering her on from the players box.

But no amount of support, royal or otherwise, could lift Williams to the level she needed on Saturday, Andreescu breaking the former world number one to open the final and never letting her opponent get her nose in front.

Williams's power game has never been in question. Her serve and crushing forehands can still strike fear into opponents.

But the rest of Williams's game has begun to show signs of wear of time.

She can no longer command the court the way she once did, and her coach Patrick Mouratoglou suggested Williams's greatest weapon – her unshakable confidence – had faltered under the weight of her own high expectations.

Before the US Open the air of invincibility that once surrounded Williams had all but vanished.

Then she arrived at the doors to Flushing Meadows and looked unbeatable, steamrolling her way into her 10th US Open final.

This was not an old Williams. This was the Williams of old.

Vintage Williams.

Any concerns over the back spasms that forced her to quit the Toronto final and pull out of Cincinnati were eased when Williams opened her Flushing Meadows account with a 6-1, 6-1 demolition of old rival Maria Sharapova.

That was followed by routine wins over Karolina Muchova, Petra Martica and Cat McNally before blasting her way into the last four with a jaw dropping 6-1, 6-0 rout of China's Wang Qiang to register her 100th US. Open victory.

An even more ruthless 6-3, 6-1 semifinal win over fifth seed Elina Svitolina seemed to indicate that the title was there for the taking.

But on Saturday she was looking across the net at a mirror image of her younger self.

A player with a big serve, thundering forehand, all court game, intensity and a cat burglar's cool.

Down a set and 5-1 the stress and frustration was written all over Williams's face.

Then the spirit of a champion took over, Williams fighting off match point and sweeping through four games to level the set and sending a jolt of electricity through a seething Arthur Ashe Stadium.

But in the end youth was served, Andreescu living up to expectations and Williams unable to live up to her own. — Reuters