Carlos Alcaraz on Wednesday doubled down on his criticism of the demands of the tennis calendar, saying "a lot of players" agree with him and "we have to do something about it".
The four-time Grand Slam champion last week said at the Laver Cup that the schedule is "going to kill us," adding his voice to the growing number of players speaking out.
The 21-year-old Spaniard is in action this week at the China Open, his 15th tournament of the year.
"I've seen and I've heard a lot of players complain about the schedule, about the calendar as well," he said.
Not among them is world No 1 Jannik Sinner, who made light of the issue when he spoke to reporters in Beijing on Tuesday.
"The schedule is quite long obviously these years. But we players, we can still choose what to play and what not to play," said the Italian, who this month won the US Open for his second major crown.
Addressing those comments, Alcaraz conceded that "it's about different feelings in every person", but added: "So I'm talking about myself, that the schedule, it's been so tight since the first week of January till the last week of November.
"We have to talk about it ourselves and we have to do something about it."
Alcaraz, the second seed, faces France's Giovanni Mpetshi Perricard in his opening match in the Chinese capital.
Top seed and defending champion Sinner plays Chile's Nicolas Jarry.
Novak Djokovic is not in Beijing while world No. 2 Alexander Zverev pulled out.