I'm going to start beginning pre-game posts with the "Who to root for" chart we began yesterday. Lots of countries who would do well to see Iran pull off the shocker. Which is too bad since...
Iran pulling off the upset is very unlikely. Iran's chance of winning is only 5%, Argentina is more likely to win 4-0 than Iran is to win, and the most likely Iran winning score (0-1) is about as likely as an Argentine 4-0 win. So good luck Iran? I always root for upsets, but yeesh.
If Iran WERE to pull of the upset, they'd be in a much stronger position to advance. Especially if Nigeria also pulls an upset (note the bright green middle of the Iran box). Even with a loss Iran would still have a shot left!
Argentina of course, is in if they win, also probably in if they don't.
This post has a little more on how the win probability graphs work
This post has a little more on how the predicted outcomes charts work
This post has a little more on the "Who should I root for" section