Cricket's international governing body has given the go ahead to a test championship and one-day international league and also told countries they're welcome to experiment with four-day tests.
A test championship has long been mooted to make the game more relevant as fans increasingly turn towards limited-overs matches.
The ICC's Chief Executive Dave Richardson said details still need to be worked out but the test championship will begin after the 2019 World Cup and culminate with a final in mid-2021.
Nine of the 12 test-approved countries, Zimbabwe, Afghanistan and Ireland will initially be excluded, will play three home and three away series over the two years that count towards the championship.
The series can be a minimum of two matches and maximum of five, with all tests to be five days in length. The top-two teams in April 2021 will meet in the final two months later.
A 13-team one day league will be introduced from 2021 and determine which teams qualify for the World Cup two years later.
"The approval of both leagues is the conclusion of two years of work from the members who have explored a whole range of options to bring context to every game," said Richardson.
"The ICC Board decision means we can now go and finalise a playing schedule ... as well as the points system, hosting arrangements and competition terms."
Richardson said countries were welcome to experiment with four-day test matches but they would not count towards the championship.
South Africa will play Zimbabwe in cricket's first four-day test on Dec. 26th and Richardson said that while the concept was still in the trial phase it should help Afghanistan and Ireland, who were granted test status in June, get up to speed faster.
"Throughout the discussions about the future of test cricket it became clear that whilst context is crucial we must also consider alternatives and trial initiatives that may support the future viability of test cricket," Richardson said.
"The trial is exactly that, a trial, just in the same way day-night tests and technology have been trialled.
"Four-day tests will also provide the new test-playing countries with more opportunities to play the longer version of the game against more experienced opponents, which, in turn, will help them to hone their skills and close the gap with the top nine ranked teams."