Four-day Test matches could become mandatory as part of the World Test Championship from 2023, but Virat Kohli isn't in favour of the proposal. The India captain, who has recently been at the forefront of boosting the image of Test cricket in the country, reckoned that tinkering too much with Test cricket will have an adverse effect on the health of the format.

"Four-day Tests? Look, I'm not a fan of [it]," Kohli said on the eve of the T20I series opener between India and Sri Lanka in Guwahati. "I think the intent will not be right then because then you will speak of three-day Tests, where do you end? Then you speak of Test cricket disappearing. I don't endorse that at all.

"I don't think that's fair to the purest format of the game - how cricket started initially and five-day Test matches was the highest of tests you can have at the international level. According to me, it shouldn't be altered."

In 2018, Kohli had also raised concerns over ECB's 100-ball competition that is set to kick off later in 2020. Kohli had said that he was "hurt" by the commercial side of cricket assuming top priority over "real quality" of the game.

On Saturday, Kohli echoed similar thoughts and suggested that day-night Test cricket is the "most that needs to be changed" in the longest format.

"I was asked about the 100-ball [cricket in England], I said I'm not going to try myself in another format because there's already so much going on and with Test cricket I don't think we need…Day-night cricket is the most that needs to be changed about Test cricket, according to me. I mean then you're purely going to be talking about getting the numbers in and entertainment."

India were initially reluctant to play day-night Tests because of the unfamiliarity of the format and challenges of sighting the pink ball. In May 2018, India had rejected Cricket Australia's proposal to play a day-night Test at the Adelaide Oval. However, the comfort of playing at home, in Kolkata, prompted India into becoming among the last sides in joining pink-ball Test cricket by playing against Bangladesh.

India's first day-night Test last November attracted sell-out crowds, and now there's a possibility that India might play another day-night Test in Australia, later in 2020.

"Day-night [cricket] is another step towards commercialising Test cricket and creating excitement around it, but it can't be tinkered around too much. I don't believe so."

The concept of regular four-day Test cricket has divided opinions in the past week. England captain Joe Root had backed it, saying "it's worth trialing" while the likes of Nathan Lyon and Glenn McGrath, much like Kohli, were against fiddling with the longest format.

The ICC is likely to formally consider four-day Test cricket later in 2020 in order to free up calendar that is clogged with too many matches and T20 leagues.