Canadian Denis Shapovalov, the number 27 seed at Wimbledon, was knocked out by Argentina’s Mariano Navone in the first round.
He was broken six times by his opponent as he suffered his earliest exit at the tournament since 2019.
“The balls are the worst, the grass tour has turned into a joke,” he said after his defeat.
“This isn’t grass anymore, the court is slower than a clay one. It’s not even grass.”
Two-time champion Petra Kvitova said things had changed over the years.
“I’m not sure if it’s only grass,” she said after her final appearance at the All England Club ended in a defeat by 10th seed Emma Navarro.
“Maybe it’s the balls, as well. Overall it’s getting slower.”
Eight top-10 seeded players have exited in the first round – the highest tally at a single Grand Slam event in the Open era.
Among those to be knocked out was American third seed Jessica Pegula, who said the courts at Wimbledon “felt different” but added: “That’s grass – they’re all kind of different. It’s a living surface, they’re not going to play the same.”
Poland’s former world number one Iga Swiatek, who beat Russian Polina Kudermetova 7-5 6-1 in her first-round match, feels the Wimbledon courts are playing slower but expects things to change in the coming days.
“It [Wimbledon] was slower, and kind of more slippery with the movement,” she said.
“But also with the heat and everything the ball bounced differently than how it will in the coming days, so I’m not really focusing on that.
“With the change of the weather we will have to adjust every day to the different conditions.”