As Serena fights for the throne, a duchess is expected to watch

NEW YORK, Sept 7 (Reuters) - As excitement boiled over for Serena Williams' latest bid for U.S. Open glory, some off-court news buzzed about the plaza at Flushing Meadows: a duchess is coming to Queens.

Meghan Markle, the wife of Britain's Prince Harry, is expected to sit in the player's box of her good friend Williams whe she takes on Canada's Bianca Andreescu in the women's final on Saturday, according to tournament organisers.

The presence of the Duchess of Sussex will heap even greater significance on what could be a memorable tennis occasion as Williams looks to add her name to the record books by equalling Margaret Court's tally of 24 Grand Slam singles titles.

While the sight of royalty at Wimbledon is as common as strawberries and cream, Markle's appearance in New York is sure to stun, even among the throngs of A-listers that regularly flock to the tournament.

She is not, however, the first royal to appear at the final Grand Slam tournament of the year.

Princess Beatrice of York attended the men's semi-final match between Rafa Nadal and Juan Martin del Potro in 2017 and Queen Sofia of Spain attended the 2013 men’s final to support Nadal, tournament organisers said.

Yet Markle stands apart as one of the most recognisable faces in the world, after her 2018 wedding to Prince Harry, an event that commanded the global spotlight.

'I USED TO CALL YOU MEGHAN'

Williams has a long-standing and well-documented friendship with Markle, with the six-times U.S. Open champion attending her royal wedding last year and, according to numerous media reports, co-hosting her baby shower in New York.

She celebrated the release of Markle's cookbook a year ago in a Twitter post that pulled back the curtain on her friendship with the former actress.

"I used to call you Meghan (and I still do) but dear Duchess of Sussex your first project 'Together' a cookbook bringing women of all cultures together. I could not be more excited about it and proud of you," she tweeted.

Markle, appearing an equally devoted friend, made the last-minute decision to fly to the Big Apple after seeing Williams beat Elina Svitolina in her semi-final, according to the Times.

When she arrives on Saturday, she'll take one of the most sought-after spots in sport.

Demand for tickets to see whether Williams could capture an elusive record-equalling 24th major title was at a similar level to a year ago when she fell in the final to Naomi Osaka.

Yet demand for tickets to this year's showpiece match was 33% higher than in 2017 when Williams did not play in the final, according to StubHub.

The retailer showed tickets costing hundreds of dollars just to get into the Flushing Meadows facility on Saturday. (Reporting by Amy Tennery Editing by Toby Davis)