New Zealand Cricket has joined the move to consider four day test matches.
The international calendar for 2023 and beyond will be sorted out this year and the England and Wales Cricket Board is offering cautious support for the radical proposal.
While five-day tests have been the norm since 1979 and many of the format's most exciting finishes have been decided on the final day of play, the ICC have the support of a number of the sport's governing bodies including Australia, England and New Zealand.
New Zealand Cricket's chief executive David White told Radio Sport's Elliott Smith four day tests would free up the calendar a bit.
"One of challenges is the calendar is very contested with ICC events, the test championship and bilateral cricket," he said.
"Having four day test matches frees up the calendar a bit. If you could have a test match on a Thursday, Friday, Saturday and Sunday it's certainly makes it easier to plan.
"But there's a lot of consultation which has got to go through and particularly with the players. They are the reason we have the game and we have to consult them as well."
There have been immediate rifts within the playing ranks, with Australian captain Tim Paine and spinner Nathan Lyon amongst those vehemently opposed to the change, along with the New Zealand pace bowler Neil Wagner and South Africa's Vernon Philander.
Lyon said: "you need time for the pitch to deteriorate and bring spinners in more on day five as well. I'm totally against it and I hope ICC aren't even considering it."
Wagner said: "If you look at the test matches that have gone five days and into a last session, they're some of the most exciting tests in history - and there's been quite a few in the last year or so."
Former test captains Mark Taylor and Michael Vaughan are open to the change, and England wicketkeeper Jos Buttler said the game must be "open to change".
"I think the administrators and broadcasters have got to look at the best way to preserve test cricket. It's the best form of the game, so how can we maintain that and keep moving the game on?" Buttler told Test Match Special.
Four day matches have been allowed since 2017 and England scheduled one against Ireland but it only lasted for three days.
Leading UK cricket writer Scyld Berry has argued the essential nature of test cricket would be destroyed by the change.
"A five-day test is a fight to the finish. It is dog-eats-dog, primeval and thrilling. You win or lose. Time is not a consideration. A draw is highly unlikely (none even in rainy England from 2016 until last summer). It is the law of the jungle transferred to a playing field. When all the frills and niceties are stripped away, it is a fight for survival," he wrote in a column for the Telegraph.
"But if you make every test a four-day game, time comes into it and offers the lesser team a place to hide. Not dog-eats-dog, but containment, and negativity, in pursuit of a draw. Thus a dramatic contest is watered down into sparring.
"The tempo of test cricket should not be speeded up any further than it is already. There should be quiet periods - as in any human activity which lasts all day for days on end - as well as exciting ones."