The US Open will mark the 25th anniversary of the 9/11 attacks, with Arthur Ashe Stadium glowing light blue from dusk until dawn. American flags will fly at half-mast as New York remembers the 2,977 people who died when hijackers crashed passenger jets into the Twin Towers in Manhattan in 2001.

That year's US Open had concluded just two days earlier, with Lleyton Hewitt winning the men's singles title. American player James Blake had lost in the second round and was in Augusta, Georgia, on 11 September. The New York-born future world number four says the day "shattered the guise of safety" felt by Americans and many professional tennis players.

"It was something that I just couldn't believe could happen in the States," Blake told BBC Sport. His father was still in New York, where he worked. With mobile networks overloaded, there was an uncomfortable wait to discover he was safe.

There will be a minute's silence before both of Friday's men's singles semi-finals. Before the night session, a giant flag will be unfurled on court as R&B artist Jo Jo sings The Star-Spangled Banner. "To me it's a really poignant moment," Blake added.