The worst Iran can do at this stage is to qualify as the third team for the play-off series, it is a hard and challenging task which will probably involve travelling a long distance to the other side of the World to Latin America. At the moment, both Lebanon and Qatar are realistically out of the competition for the top three spots, although mathematically Qatar is still in with a slim chance provided Iran loses against Lebanon in Azadi while Qatar scores a wide margin victory in their last match away against Uzbekistan. Such victory will take them to 10 points and in par with Iran who still has a match to play against the Koreans. Any points from Korea by Iran, and Qatar is out.
More realistically, the competition will be between the three current top teams in Group A, Korea Rep, Uzbekistan and Iran.
Next Tuesday will see the two top teams, Korea Rep and Uzbekistan facing off in Seoul. While Iran would be entertaining the bottom team Lebanon whom they have already trounced this year 5-0 in the 2015 Asian Cup qualifiers. Assuming Iran wins the match against Lebanon by any margin making their points tally 13 , the hopes are for the first match to end up with a draw giving Korea Rep 12 pts ( GD +6) , Uzbekistan 12pts (GD +2) and Iran 13 pts (GD +2 or better).
That will make the last round; the decider round between the three teams concerned where Iran will travel to Korea for their last match and Uzbekistan will face Qatar at home.
Iran needs a draw from Ulsan to qualify directly to Brazil accumulating 14 pts to Koreas 13 ( or 14 pts if they beat Uzbekistan in the previous round). Uzbekistan needs to beat Qatar by any goal margin to accumulate 15 pts to qualify ( assuming they drew with Korea previous round). with 14 points (if they lost to Korea), the Uzbeks might be looking at goal margin.
In case Korea Rep defeats Iran in Ulsan (15 pts) against Iran’s 13 pts. Uzbekistan needs to beat Qatar to get 15 pts, Iran will be playing in the play-off against the third rank team of the Group B.
If Either of the teams Korea Rep or Uzbekistan win that match next week ( the winner gets 15 pts (loser still on 12) , then Iran need to draw at least in the last round against Korea to make it directly (14 pts).
In all cases , to ensure Iran qualifies directly, they need a win in Azadi versus Lebanon and at least a draw in Ulsan against their nemeses Korea Rep.