Alexander Zverev on Saturday accused tennis authorities of favouring top-ranked rivals Carlos Alcaraz and Jannik Sinner in their choice of court surfaces, echoing criticisms made by Roger Federer.
Some in tennis have charged that court surfaces in tournaments have become too standardised and generally slower, which could give an advantage to certain players.
Asked his opinion after his straight-sets victory over Valentin Royer at the Shanghai Masters, Zverev was unequivocal.
"I hate when it's the same," said the 28-year-old German, who is ranked third in the world, behind Alcaraz and Sinner.
"I know the tournament directors are going towards that direction because obviously they want Jannik and Carlos to do well at every tournament, and that's what they prefer."
His comments match those made by Federer on the sidelines of the Laver Cup last month.
The 20-time Grand Slam winner said there was "definitely" a need to change up court surfaces to amp up competition.
He, too, accused tournament directors of giving a helping hand to Sinner and Alcaraz with generally slower courts.
Asked about Federer's comments, Sinner agreed there was little variety in court speeds on tour.
"This is how it is already since a long time," he said recently in Beijing.
"I'm just a player who tries to adapt myself in the best possible way."
Zverev said he had seen a big change over a decade of playing professionally.
"You couldn't play the same tennis the same way on a grass court, hard court, or clay court. Nowadays, you can play almost the same way on every surface," he said.
"I'm not a fan of it, I think tennis needs game styles... a little bit of variety, and I think we're lacking that right now."