New York: Fireworks, strobe lights, thumping music and gyrating dancers on the court of Arthur Ashe Stadium. It can only mean one thing: the official start of the US Open.

John McEnroe and Martina Navratilova, singles champions from three decades ago, slammed tennis balls into the stands before Monday night’s matches to ceremonially light the Empire State Building in US Open court blue.

And first-year New York City Mayor Bill de Blasio officially welcomed the 700,000 fans to the two-week tournament, saying “the US Open is where it’s at!”

That was all a prelude to pounding rock tunes from the band Fitz and the Tantrums, accompanied by booming fireworks, flashing strobe lights and a team of dancers gyrating on the court over projected images of the game’s biggest stars.