A patron walks under an umbrella after rain postponed matches at the US Open tennis tournament in New York, Sept 6, 2011. [Photo/Agencies]
On the eve of the tournament, New York was battered by Hurricane Irene and now the remnants of Tropical Storm Lee are drenching the eastern seaboard and threatening to ruin the second and final week of action.
For the world's best players, the next few days shape as a race to beat the weather and a test of their patience as much as their power and skill.
Tuesday's entire programme was cancelled before a ball was hit because of showers in New York and the forecast for the rest of the week is just as bleak.
The postponement left tournament officials with a backlog of matches and forced them to reorganise Wednesday's schedule. Instead of four singles matches on the Arthur Ashe centre court, there will be 10 singles encounters spread over three courts.
Each of the 20 remaining players - 12 men and eight women - will be in action on the same day, providing a galaxy of stars for the tennis fans at Flushing Meadows but raising doubts over whether all the matches will be finished in time.
For some players, the delays and interruptions are a nuisance. For others, they may come as a welcome relief.
Patrons wait for play to begin at Arthur Ashe Stadium after rain postponed matches at the US Open tennis tournament in New York, Sept 6, 2011. [Photo/Agencies]
Rafa Nadal collapsed after his last match because of severe cramps caused by the intense humidity on court. The prospects of cooler temperatures for his clash with Gilles Muller of Luxembourg would hold obvious appeal.
Nadal's match is one of four fourth-round clashes still to be played and has been pushed to the front of the queue with organisers hoping to get those done before starting the quarter-finals.
Andy Murray and Andy Roddick, both originally scheduled to play on the Arthur Ashe Stadium, have had their matches moved to smaller showcourts, which are not normally used at this stage of the tournament, to try and speed things up.
Roddick plays fifth seed David Ferrer of Spain at Louis Armstrong Stadium while Murray tackles American wildcard Donald Young on the Grandstand Court.
All four women's quarter-finals have been added to the schedule. Williams plays Anastasia Pavlyuchenkova in the night session while world number one Caroline Wozniacki is due to meet Andrea Petkovic.
The first two men's quarters have also been fitted in, with world number one Novak Djokovic locking horns with his Serbian Davis Cup team mate and Federer set to square off with Jo-Wilfried Tsonga in the late match.
"Look, if the rain comes, that's what it is. You can't change that," Federer said. "We've had to come back the next day several times already. That's just a part of our game."