Widmaier said that during the summer, the U.S.T.A. had made it clear to players, their representatives and leaders of both the Association of Tennis Professionals and the Women’s Tennis Association, which represent players and the leaders of tennis tournaments, that players who tested positive would be withdrawn from the tournament and would have to go into quarantine in New York. Players who had come into contact with any player who tested positive would be subject to local health regulations, too.
However, Widmaier said, the organization did not have a final plan for what would happen to players who continued to test negative after they had been exposed to players who tested positive. Also, while the U.S.T.A. worked closely with health officials in New York City and with Gov. Andrew M. Cuomo, it did not work closely with officials in Nassau County, even though the player hotels are there.
Last weekend, after Paire’s positive test, U.S.T.A. officials scrambled to produce a new set of rules for players who had had extended contact with him but whose tests were negative. The rules, which received the approval of health officials in New York City, included daily testing and isolation from the rest of the players, including separate buses, use of hotel stairs instead of elevators and no access to common areas at the National Tennis Center. To remain in the tournament, players had to sign an agreement saying they would adhere with the rules.
Those rules remained in place until Friday, when health officials in Nassau County distributed notices at the player hotels spelling out their decision that the players who had been exposed to Paire would be required to remain in their rooms until the end of their quarantine period next Saturday.
Adrian Mannarino, one of the exposed players, was at the National Tennis Center at the time. For nearly three hours, tennis officials negotiated with state health officials over whether he would be allowed to play his scheduled match with Alexander Zverev of Germany. The match, originally scheduled for 2:30 p.m., began at 5 p.m. Mannarino lost and said after the match that he would return to the hotel to enter quarantine.
That appeared to clear the way for Mladenovic to play her doubles match, which was scheduled for Saturday, but the match was removed from the schedule before play started.
Daniil Medvedev of Russia, who was shown through contact tracing to have had some contact with Paire before his positive test, won his third-round match Saturday afternoon. For now, it appears that he will be able to remain in the tournament.