London - The opening day of the Ashes series between England and Australia at Edgbaston on Thursday also marks the start of the International Cricket Council's (ICC) new World Test Championship.
The aim is to give individual Test series greater context and spark a worldwide revival of interest in the five-day game.
What is it?
The top nine nations will compete in a total of 72 Tests across a two-year period, with the aim of determining the best Test team in the world.
The teams involved will be Australia, Bangladesh, England, India, New Zealand, Pakistan, South Africa, Sri Lanka and West Indies.
The two teams who top the points table over that period will then play each other in a one-off World Test Championship final at Lord's in June 2021, before a new cycle starts.
Each team will play three series at home and three away, consisting of two, three, four or five Tests.
There will be 120 points available per series shared out equally over the number of matches - so a five-Test series has 24 points per match available to the winner and a three-match campaign 40.
If the match is drawn, points are awarded on a 3:1 points ratio - so in a Test where 60 points are available for a win, a draw will see both sides take 20.
Matches involving Afghanistan, Ireland and Zimbabwe will still have Test status but the results will not be counted in the World Test Championship.
"Test cricket is the pinnacle of our sport," said England's leading Test wicket-taker, James Anderson, in an ICC statement.
"It is the very essence of cricket and the majority of players want to strive to play the purist form of the game. The ICC World Test Championship is another brilliant initiative for the sport, adding context and relevance to every Test series. Every Test matters, but even more so now."
Australia captain Tim Paine said: "If the World Test Championship helps to ensure that all countries make Tests a high priority then that has to be good news for the game in general and the continuing health of the format in particular."
India skipper Virat Kohli said: "We are awaiting the ICC World Test Championship with great enthusiasm as it adds context to the longest format of the game.
"Test cricket is very challenging and coming out on top in the traditional form is always highly satisfying. The Indian team has done really well in recent years and will be fancying its chances in the championship."