Top 10 Moments of 2021: Storm Ida sweeps through Flushing Meadows

7. Through the Roof: Indoor rain delay at Flushing Meadows

Rain delays are as traditional in tennis as grass and wristbands, but this was something else again. A rain delay indoors—spectators wading through ankle-deep water, and fountains spontaneously erupting on the grounds.

That was Day 3 at the US Open, when the remnants of one of the season's strongest hurricanes swept through New York and prompted a flash flood warning.

When the full storm hit there were just the night sessions on Ashe and Louis Armstrong left to finish—no problem, it initially seemed, since both had retractable roofs.The weather had other ideas.

Strong rain and gusts of wind led rain to leak through the roof on Ashe and on Armstrong, which boasts a 'natural ventilation system,' it blew in sideways through the upper portion of the stadium.

The evening on Ashe nevertheless unfolded relatively smoothly, with Sloane Stephens defeating Coco Gauff in straight sets and Stefanos Tsitsipas got by Adrian Mannarino in four sets. But Diego Schwartzman and Kevin Anderson had quite the night as their played their second-round contest on Armstrong, and the second half of the session never got on.

There was the odd sight of the court being dried and spectators opening umbrellas—indoors during the first set, and the players were slipping and sliding during the tiebreak and the conditions eventually had Anderson walking off court.

They were moved to Ashe around midnight, and Schwartzman wrapped up victory at approximately 1 a.m.— just a travel ban was issued across the city.

Some fans were stuck in their cars in the parking lot all night, others were stranded on site as subways shut down.

There was plenty of wet weather during this season's slightly extended hardcourt stretch -- showers in Toronto, even rain in the desert at Indian Wells.

But the US Open's indoor downpour was unusual even by tennis standards.