Persistent rain forced the cancellation of all matches Monday at the French Open, the first wash-out in 16 years at the clay-court Grand Slam tournament.

Organizers said abandoned matches would be rescheduled for Tuesday. But after a first week of often poor weather and with more rain forecast, they now must fit dozens of unfinished and postponed matches into an ever-smaller window for the tournament to have finals over the weekend as initially planned.

In women's singles, two fourth-round matches -- Simona Halep vs. Samantha Stosur and Tsvetana Pironkova vs. Agnieszka Radwanksa -- were pulled off court unfinished on Sunday evening because of rain and darkness. Initially rescheduled for Monday, the earliest they can now be completed is Tuesday, when quarterfinals are scheduled to start.

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Those two will now be added eight other fourth-round matches -- four men's and four women's -- that didn't even get started Monday before organizers announced in the early afternoon that there would be no let-up in the rain, washing out the entire day.

Also canceled were more than 50 matches in the doubles and junior tournaments. And there was no guarantee that Tuesday would be better: Weather bureau forecasts for coming days were grim, with more downpours expected Tuesday before a hoped-for break in the clouds on Wednesday.

The washout highlighted one of the enduring weak spots of the cramped Roland Garros site in the west of Paris: its total lack of roofs over courts and delays to its plans to start tackling the problem.

The French Open is the only major tournament without a structure for play to continue under rain.

No roof is expected over Roland Garros' Court Philippe Chatrier before 2020, pushed back from 2018.

The last total wash-out in Paris was May 30, 2000, according to organizers.

With no play at all Monday, ticket holders were told to apply for refunds.

The schedule, weather permitting, for Tuesday has top-ranked Novak Djokovic against 14th-seeded Roberto Bautista Agut in the first match on Chatrier, playing for a place in the quarterfinals.

They will be followed by defending champion Serena Williams in her fourth-round match against 18th-seeded Elina Svitolina. Venus Williams' match against 2015 semifinalist Timea Bacsinszky was supposed to have been played on Chatrier on Monday but was rescheduled as the third match Tuesday on Court Suzanne Lenglen.

The new schedule does still have the first quarterfinal matches: second-seeded Andy Murray against Richard Gasquet is the third match on Chatrier and men's defending champion Stan Wawrinka against Albert Ramos-Vinolas of Spain is scheduled last on Lenglen.