Paris: The French Open suffered its first rain washout in 16 years Monday, leaving tournament chiefs venting their frustration at Roland Garros' isolation as the only Grand Slam without a covered stadium.
There could be more problems on Tuesday with further heavy rain forecast throughout the day in Paris before conditions brighten on Wednesday.
Monday's washout left the French tennis federation having to refund around 30,000 ticket holders.
It also prompted tournament director Guy Forget, a former player and Davis Cup winner, to warn that France is getting left further behind the sport's three other majors -- Wimbledon, the Australian and US Opens.
All three tournaments have stadiums with roofs.
But Roland Garros will not see a roof built over its showpiece Philippe Chatrier Court until 2020 at the earliest.
"It is very frustrating but it is proof that the roof is a necessity and that we have to do it," said Forget.
"We cannot be like this for many more years. We hope to have the roof by 2020. People have to realise that nobody can stop the process.
"The world is moving fast -- we were talking about the roof 15 years ago."
Eight last-16 matches planned for Monday plus two more which had been held over from Sunday will now be played on Tuesday.
Two quarter-finals are also due to take place Tuesday -- Andy Murray against Richard Gasquet and defending champion Stan Wawrinka facing Albert Ramos-Vinolas.
Play had been set to get underway at 1100 (0900GMT) on Monday but was eventually called off just before 1400 (1200GMT).
The last washout in 2000 also happened on May 30.
"Tuesday looks better so I am fairly positive," added Forget, who explained that play will start at 0900 (1100GMT) rather than the traditional 1400 (1200GMT) on the second Tuesday.
Several delays:
This year's Roland Garros was hit by rain delays on the opening Sunday when just 10 of the scheduled 32 ties were completed in a little over four hours of play.
The second day was then hit by another two and a half hour delay. That in turn pushed 12 of the scheduled 66 matches back to the first Tuesday.
There was a two and a half hour stoppage on Saturday followed by another hour on Sunday which meant that the planned last-16 programme remained unfinished.
Under the original schedule, all of the fourth round was to be completed on Monday, leaving Tuesday and Wednesday for the quarter-finals.
If there are further delays Tuesday, world number one Novak Djokovic, who is chasing a first French Open to complete the career Grand Slam, could end up playing his last-16 tie Wednesday, quarter-final on Thursday and semi-final Friday.
Djokovic has suffered at the hands of the weather in Paris in the past.
In the 2012 final against Rafael Nadal, he had fought back from two sets to love down to take the third set and lead in the fourth when play was halted.
The final was suspended until Monday when Nadal raced to victory in just a further 50 minutes.
Djokovic will be poised to become the first man to win $100 million in prize money if he makes the quarter-finals for the 10th time.
Top seed Djokovic tackles Spain's 14th seed Roberto Bautista Agut in Tuesday's opening match.
Also in last-16 action will be women's top seed and defending champion Serena Williams who will continue her bid for a record-equalling Open era 22nd Grand Slam title.
The 34-year-old takes on Ukraine's Elina Svitolina who is being advised in Paris by Justine Henin, one of Williams' former great rivals on the tour and a four-time French Open champion.
