Supporters of Syria celebrate at the end of the FIFA 2018 World Cup qualification football match between Iran and Syria at the Azadi Stadium in Tehran, on Sept 5, 2017. [Photo/VCG]

Syria's opponent on the field Tuesday - Iran - is a regional political ally that has provided crucial political and military support to shore up Assad's forces in the war.

Qualification could have been automatically clinched with a victory in Iran, which had nothing to play for after already securing its place in Russia.

Now Syria will have to qualify the hard way for its first trip to the FIFA showpiece.

Syria will play Australia in a two-match Asian series next month. To make the World Cup, the winner will then have to beat a team from the CONCACAF confederation covering North and Central America, and the Caribbean. Syria will likely play its 'home' match against Australia in Malaysia, as it has during Asian qualifying, due to the ongoing war.

AP