New York, Sep 12 (DPA) US Open officials admitted partial defeat on a day of demoralizing rain, with women's semi-finals cancelled and the conclusion of the interrupted men's quarter-finals between Rafael Nadal and Fernando Gonzalez in danger from the weather.

Kim Clijsters and second-seeded holder Serena Williams were both told late afternoon that their match would not go on.

The same grim news was handed to Danish ninth seed Caroline Wozniacki and Belgian outsider Yanina Wickmayer.

Officials were hoping against the odds that they could somehow conclude the Nadal-Gonzalez match, which stood 7-6 (7-4), 6-6 (3-2) in the Spaniard's favour after being interrupted for a second time just before midnight Thursday.

The weather drama almost insured that the event could go into a late finish next Monday for the second consecutive year.

If that is the case, it will put even more pressure on the cash-flush US federation to spend the millions required to put a roof on one or more of their massive stadiums at the National Tennis Centre.