And the wet conditions are likely to benefit Halep, said three-times champion Mats Wilander.
Two women's and two men's quarterfinals matches have been rescheduled on Thursday, two hours ahead of the expected time.
Joanna Konta and Marketa Vondrousova are scheduled to play for a place in the final on Thursday, which means the victor of that match will have at least a day's rest more than whoever she faces for the title.
The weather is due to relent today but more rain is forecast for tomorrow.
"We saw that historically we can play men's finals on Monday", Forget said.
Top seed and defending champion Novak Djokovic continued his untroubled progress as he beat Germany's Jan-Lennard Struff 6-3 6-2 6-2 to reach a 10th successive quarter-final at Roland Garros - the first man to achieve that feat.
Sudan Protesters Say 40 Killed Since Dispersal
Protesters have remained camped out in front of Khartoum's army headquarters to pressure the generals to yield power. On Saturday, the ruling TMC issued a statement declaring that the "sit-in has become a threat to the country".
The key to her success has been remarkable returning: She has won 70% of her opponents' service games, 30 of 43, which not only leads the tournament but reads as if it's a misprint. "But I feel stronger on court", she went on to say.
In a match originally scheduled for Court Suzanne Lenglen but pushed to Court Simonne Mathieu to ensure it would finish before darkness, Anisimova moved into her first Grand Slam quarterfinal with a 6-3, 6-0 win over Spanish qualifier Aliona Bolsova.
"I am satisfied so far with my game", Djokovic said, "I reached the quarter-finals and played as closest to my best tennis on clay as I think I can be at the moment". Halep routed 18-year-old Iga Swiatek 6-1, 6-0 in 45 minutes. Coach Bruce Cassidy didn't talk to and only briefly texted with the 42-year-old defenseman, who has a facial injury that has been reported to be a broken jaw. "And the best way to get this result is for them to play their matches at the same time".
"I just wanted to leave my first Roland Garros as a professional, to try to go through the qualies and, suddenly, I'm playing the fourth round here".
On the women's side, it's No. 26 Johanna Konta of Britain against unseeded 19-year-old Marketa Vondrousova of the Czech Republic.
Back then he was seeded 20th, months after having elbow surgery, and suffered a shock quarterfinal defeat to relative unknown Marco Cecchinato that left him annoyed.