Donald Trump will become the first sitting U.S. president to attend the U.S. Open in a quarter-century on Sunday, as he joins the legions of fans in New York to catch a highly anticipated showdown between Jannik Sinner and Carlos Alcaraz.

Republican Trump has attended numerous sports events to meet with his supporters, but he may not receive the warmest welcome at the U.S. Open in deeply Democratic New York City.

He was once a fixture of the tournament before taking office, and in 2015 was booed by some tennis fans not long after launching his presidential campaign.

Ticketholders can expect extraordinary security measures at the sprawling Billie Jean King National Tennis Center in Trump's home borough, Queens, where the final tennis major of 2025 is on track for a fourth straight year of record-setting attendances.

While the pricey playground for tennis fanatics and designer-clad social media influencers regularly brings in an array of A-listers, the tournament has not seen a sitting U.S. president since Bill Clinton attended in 2000.

Barack and Michelle Obama attended in 2023, six years after the Democratic president left office.

Second seed Alcaraz said he would try not to think about Trump in the crowd as he bids for his sixth Grand Slam title.

"I don't want myself to be nervous because of it," the Spaniard told reporters on Friday after defeating 24-time major winner Novak Djokovic in the semi-finals.

"But I think, you know, attending the tennis match, it's great for tennis to have the president at the final."

MEGAWATT SPOTLIGHT

Trump is far from the first U.S. president to step into the megawatt spotlight of professional sports.

President Barack Obama appeared on ESPN to fill out his "March Madness" bracket while in office and George W. Bush famously threw out the first pitch at Shea Stadium in 2001, when the Mets took on the Atlanta Braves for the city's first major sporting event after the September 11 attacks.

But few have embraced sports' biggest events with the same gusto as Trump, particularly in his second term.

Trump grabbed headlines when he became the first sitting U.S. president to attend the Super Bowl in February, stepping into the media glare of America's most-watched annual event.

The fans at New Orleans' Superdome greeted him with a mix of cheers and boos, and he met briefly in the stadium with families of the victims of the New Year's Day attack on Bourbon Street as well as police officers and emergency workers.

Months later, Trump announced from the White House that Washington, D.C., would host the 2027 NFL Draft, an annual mega-event that regularly attracts hundreds of thousands of fans.

He attended soccer's Club World Cup final in July, where he sat in box seats at MetLife Stadium with FIFA boss Gianni Infantino and remained on the stage during the trophy lift with winners Chelsea, to the confusion of some of the players.

Days after Alcaraz and top seed Sinner play, Trump is expected to attend the New York Yankees game against the Detroit Tigers on the 24th anniversary of the September 11 attacks.

Later this month, he is expected to attend the Ryder Cup, the biennial international golf competition, on Long Island.

At the U.S. Open, Trump will attend as a "client guest," organisers said, and will watch from that guest's respective suite at the famed Arthur Ashe Stadium.

"It is a privilege for the tournaments having the president from every country just to support the tournament, to support tennis and to support the match," said Alcaraz.