With "9/11/01" inscribed alongside the centre court net, a moment of silence was observed for the nearly 3,000 people killed in the attacks and a giant American flag was unfurled over the court by a U.S. Marines Corps colour guard.
Singer and actress Queen Latifah sang a stirring rendition of the national anthem to close the tribute.
Finalists Serena Williams of the United States and Australian Sam Stosur entered the court through an honour guard comprised of members of the New York Police Department, the Fire Department of New York and the Port Authority Police.
Earlier, in downtown Manhattan at the site of where the World Trade Center twin towers stood, the name of every person killed in al Qaeda's hijacked plane attacks was read in the nearly five-hour-long centerpiece of a heart-wrenching ceremony.
Smaller ceremonies were also held in Shanksville, Pennsylvania and at the Pentagon outside Washington, the other sites where 19 men from the Islamic militant group al Qaeda crashed hijacked airliners on the morning of Sept. 11, 2001.