This will be the decider of who goes through to the quarter-final with England.
There is an unlikely permutation where Samoa can still make it if these two teams draw but that is a bit of a stretch.
If there is a draw in this game then it would be Argentina going through on a points difference, except if Japan gets a 4-try bonus point and Argentina doesn’t.
The most likely outcome will be a win for either to determine that last spot.
Japan stands a chance to reach their 2nd quarter-final in a row and Argentina can spectacularly crash out for a 2nd time in a row.
The margins between these two teams are however exceptionally close at the moment.
It is true that Argentina sits a couple of spots above Japan on the rankings but Argentina has been less than convincing over the past few months.
Japan, on the other hand, started the year with loss after loss and only picked up their first win of the year at the World Cup. Since then they have steadily improved and are real contenders to get to the quarter-finals.
When Japan is on song, they are able to carve out wins against most teams in the world, but they lack strike runners to consistently penetrate the defenses of their opponents.
This Argentinian team has certainly turned their performance around in comparison with that first half-hearted and flawed effort against England at this year’s tournament.
Although Japan has a lot going for them, I believe that Argentina will take the win.
They are more battle-hardened from playing against South Africa, New Zealand, and Australia in the Rugby Championship every year and should book their place in the quarter-finals as a result.