The International Cricket Council has confirmed significant changes to the structure of men's Test and one-day international cricket in a bid to add extra context to the international game.
After meetings with representatives from cricket boards in Auckland this week, ICC chief executive Dave Richardson confirmed a nine-team Test Championship and 13-team ODI League would be introduced from 2019 and 2020 respectively.
The Test Championship, which is set to begin in July 2019 - when Australia will be in England for an Ashes Test series - will see nine of the 12 Test nations (excluding newcomers Ireland and Afghanistan, as well as Zimbabwe) play six series over two years – three home and three away.
Each bilateral Test series will feature at least two Tests and a maximum of five, with the Championship to culminate in a 'World Test League Championship Final'.
The Final will be played in June 2021 but the ICC haven't confirmed where the match will be played. Lord's, the traditional Home of Cricket, has been previously touted as a likely venue.
Every Test series will have the same number of points on offer regardless of how many matches are played in the series, though the points system is yet to be finalised.
The ODI league, set to begin in May 2020, will feature the 12 full (Test-playing) ICC members plus the winner of the current ICC World Cricket League Championship.
Each side will play four home and four away series each comprising three ODIs in the first edition of the league and will provide a direct qualification pathway to the 2023 World Cup, to be held in India.
Further details around the Test Championship and ODI League are still to be confirmed, ICC chief executive Dave Richardson said.
"This is a significant point in time for ICC members and our collective desire to secure a vibrant future for international bilateral cricket," Richardson said in an ICC statement.
"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.
"The ICC Board decision today means we can now go and finalise a playing schedule for the first edition as well as the points system, hosting arrangements and competition terms."
The ICC also confirmed four-day Test matches will be permitted on a trial basis until the 2019 World Cup but will operate outside the new Championship structure.
International boards are now free to arrange four-day Tests by bilateral agreement, as South Africa have already done with their proposed four-day Boxing Day Test against Zimbabwe later this year.
Richardson suggested the shortened Tests would provide newcomers Ireland and Afghanistan with the chance to "close the gap" between them and leading Test sides.
"Our priority was to develop an international cricket structure that gave context and meaning across international cricket and particularly in the Test arena," Richardson explained.
"This has been delivered and every Test in the new league will be a five-day Test format.
“However 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.
"The trial is exactly that, a trial, just in the same way day-night Tests and technology have been trialled by Members.
"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."
There is also scope for the lower-ranked Test teams to play each other, and some of the leading Test nations in one-off games, in the longest format outside of the new structure.
In ODI cricket, teams will have to arrange to bilateral series outside of the new international 50-over structure during the 2019-20 and 2022-23 seasons.
Crucially however, the ICC have mandated that no bilateral ODIs are to be played outside of the new structure amongst the 13 competing teams during the two-year league period.
The ICC said it expected the second and subsequent editions of the ODI League (starting after the 2023 World Cup) would be held over three-year cycles, with all teams playing each other towards qualification for next World Cup.