Heavy balls and cold weather had players complaining as the French Open began, with not much change expected for the first week.
The tournament, usually played in springtime, is also limited to 1,000 fans a day because of coronavirus restrictions.
On the first day, Victoria Azarenka asked for play to be stopped because of the cold and complained when asked to stay on court.
"No, it's completely ridiculous. It's too cold, what's the point, sitting here like ducks," she said.
There was also rain as the second day began. But the tournament has a new roof, allowing play to keep going on its biggest court.
It is also using a new ball produced by Wilson, which has been described as larger and heavier by players. Dan Evans went a bit further following a five-set defeat.
"Some of those balls we were using you wouldn't give to a dog to chew," he said. "It's brutal. It's so cold. I think the balls are the biggest thing."
The heavy balls and cold weather both slow the play, he added.
"Maybe they got it a little wrong with the balls,” Evans said. “It's tough to get that ball to go anywhere... That ball's a bit too heavy, I think."
Kei Nishikori, who won against Evans, agreed. "But for sure there’s less bounce. Especially today it didn't bounce," said Nishikori.
That backs up Rafael Nadal's assessment from the day before, when he called the balls "super slow, heavy" and noted the "cold" temperatures.
According to John Isner, soggy clay also makes it more like a "slow hard court" rather than the slippery red stuff.
Players have had to adjust. "I'm stringing three kilos less than I did in New York," said Zverev.
Still, players are back competing, playing their second Grand Slam following a five-month hiatus. Even Azarenka said she prefers the tournament being played, especially since "lower-ranked and doubles players were hit pretty hard" during the break in competition.
"But it's nice that we have the chance to play," said Simona Halep.
"At least only thing we can say is... we can play tennis again," added Nadal.
The tournament is being played with safety protocols and the approval of local authorities.