And now, the end is near. And so we face the final curtain. A bit dramatic for the end of the group stages of a Twenty20 World Cup, but soon eight teams out of a dozen will be heading home or to their next assignments, thinking about what might have been and the disappointment of what wasn’t. And in Group 1, at least, the matter of which two teams get to stay a little longer will come down to pure and beautiful arithmetic.

Arriving at this tournament, England and Australia would have been worldly enough to know that they couldn’t expect to walk out of this group. They were diplomatic enough to cite every opponent as a tough competitor who could beat them on a given day. They were seasoned enough to know that this was true. And in their hearts, they would still have known that they should be the two to progress. The two biggest and best-resourced teams, one the host, the other the pace-setter in short form cricket for the last seven years.

Australia weren’t expecting to get thrashed by a New Zealand side that routinely folds against them. England weren’t expecting to get jumped by Ireland and a spot of Melbourne rain. So with one game left to play, the big dogs sit level with New Zealand on wins, losses, and washouts, separated only by net run rate: the measure of how quickly a team scores its runs compared to how quickly it concedes them.

Ahead of their final round, let’s take care of the caveats. Yes, Ireland have built a good side after the departure of the golden generation players who won their country full member status at the ICC. There is an Irish giant-killing history at World Cups, and they could beat New Zealand on Friday. Yes, Afghanistan will be playing on a used Adelaide Oval pitch, and can deploy quality spin against an Australian team that still has weaknesses against it. Yes, Sri Lanka on a good day are more than capable of beating England in Sydney on Saturday, even if their bad days have been prevalent in this tournament.

And with all that said, none of those things are likely to happen when those teams face off in Adelaide. If New Zealand, England and Australia all bank an expected win, New Zealand stay top of the table, thanks to two big margins to start the tournament that gave their rate a supercharge. For England to bridge that gap would mean beating Sri Lanka by about 140 runs or chasing a score in five overs. Put that in the category of theoretically possible but functionally impossible, the same as the minute but extant chance that either Sri Lanka or Ireland could still make the semis with a combination of multiple upset results and absurd run-rate shifts.

What is possible, and for that reason a lot of fun, is that Australia supplanting England is possible. In a normal range of scores, with a variance of one or two runs, Australia would need to beat Afghanistan by about 62 to catch England’s rate. So if England win, Australia need to be 62 runs beyond their margin. If bowling first, it’s not just about keeping the opponent to a low score, but the high-speed pursuit. If Afghanistan make between 100 and 160, Australia have between 12.2 and 13.1 overs to level England, plus whatever margin England could achieve.

It’s a tall task, and the ramifications of Australia letting Ireland back into the game from 25-5 on Monday night become all the more stark. But it is possible. And the extra fun part is that Australia play on Friday, England on Saturday. So the Australians will have to go absolutely hell for leather, needing to exceed England’s mark but not knowing by how far. And if they do, England will have to thrash a talented team to catch up. It will change batting orders, tactics, the whole dynamic, in ways that also give underdog teams an opening. It keeps the group alive to the last game. As long as New Zealand do their job against the Irish, then finally this world will have something for the arithmeticians. Divide, subtract, and conquer.