PHOTOS: US Open pauses to remember 9/11 under heavy security

The US Open reached an emotional climax on Sunday as the year's final grand slam paused amid heavy security before the start of the men's singles to remember those who died in the 9/11 attacks 15 years ago.

As heavily armed law enforcement officers and bomb sniffing dogs patrolled the sprawling Billie Jean King Tennis Center, a packed Arthur Ashe Stadium with 9/11/01 stenciled into the court observed a moment of silence followed by a flyover of four F-15E Strike Eagles.

The US Open's Flushing Meadows home is just 10 miles to the northeast of the site of the former Twin Towers of the World Trade Center, the 2001 attacks left a mark on the sprawling facility and many players.

At the Open in 2001, a 20-year old Australian Lleyton Hewitt defeated American Pete Sampras to win the men’s final two days before the attack.

Several of the players in that year’s tournament left New York on flights in the days and even hours before the Twin Towers came down.

Over the years since, scores of top tennis players from around the world have made their way to the site of the Twin Towers.

Spain's twice US Open champion Rafael Nadal, who was 15-years-old in 2001, has said he has gone to memorialize the 9/11 victims at least a half dozen times over the years.

Serb Novak Djokovic, who played Swiss Stanislas Wawrinka in Sunday's final, in 2009 invited several children of 9/11 victims to see him play at the Open.

American Bethanie Mattek-Sands, who began Sunday's action on Arthur Ashe Stadium court partnering with Lucie Safarova, paid her own tribute wearing Stars and Stripes knee-high socks and wrist bands.

"It is an emotional day," said Mattek-Sands, who won gold at the Rio Olympics in mixed doubles with Jack Sock. "I was going to retire my American flag socks after the gold medal match.

"I said, You know what? For the final of the US Open, 9/11, have to bring them out.

"It was really special for me to win it here today in New York."

In Lower Manhattan on Sunday morning, thousands gathered at the 9/11 memorial site to commemorate the 15th anniversary, as police, firefighters and rescue workers mixed with victims’ families and US presidential candidates Hillary Clinton and Donald Trump.

Clinton left the ceremony early after feeling unwell on a hot, humid day.