India captain Virat Kohli on Saturday hit out at proposals to cut Test matches from five days to four as the world body battles with the crowded cricket calendar.
Reports that the International Cricket Council could decide to cut the length of Test matches from 2023 have divided players and nations.
Kohli, who leads the world Test batting rankings as well as being captain of the number one Test side, said the format should not be altered.
"Day-Night Tests is the most that should be changed about Test cricket, according to me," Kohli said in Guwahati, ahead of India's T20 game on Sunday against Sri Lanka.
With four-day Tests "you are purely only talking about getting numbers in and entertainment, and I think the intent will not be right," said Kohli.
"Then you will speak of three-day Tests. I mean, where do you end," he added.
"I don't endorse that (change) at all. I don't think that that is fair to the purest format of the game -- how cricket started."
"Day-night tests are another step on commercializing Test cricket and creating excitement around it, but it can't be tinkered with too much."
Day-night Test were also initially resisted by players, but have become gradually accepted.
The ICC allowed four-day Tests in 2017 and they have been tried in one-off games between South Africa and Zimbabwe and England against Ireland.
But they are not allowed in the Test world championship which is led by Kohli's India.
The English, Australian and New Zealand national associations have indicated they are ready to change. Some players like England captain Joe Root have also said the plan should be considered.
But the key Board of Control for Cricket in India has not yet made a comment. And several leading players have joined Kohli in coming out against the change.
Australia captain Tim Paine said that while four days could be used for some Tests, the main games had to stay at five.
Australia's most successful off-spinner Nathan Lyon has called the idea "ridiculous".
"I believe you will get so many more draws and day five is crucial," he told the Unplayable Podcast before the recent Test against New Zealand.
"I?m totally against it and I hope ICC aren't even considering it."
The ICC and national boards in favour of change say that cutting Test time is a way to ease a calendar now packed with Tests, 50 over internationals and the growing number of T20 internationals and leagues.
India's captain Virat Kohli says the five day Test match format should not be altered
Indian cricket team captain Virat Kohli (C) leads the world Test batting rankings and is captain of the number one Test side