Beat Iran – who conceded six times to England only a few days ago - and Rob Page’s side have a great chance of qualifying for the knockout stages of their first appearance on football’s grandest stage in 64 years, following Monday’s spirited comeback draw with the USA.
Lose, however, and they face a very nervous wait to see what happens on the final match day, when they are to play rivals England.
Either way, it promises to be a must-watch affair. Here’s how to catch all of the action from Qatar this morning.
Where to watch Wales vs Iran
TV channel: The game will be broadcast live free-to-air on BBC One and Welsh language channel S4C.
Live stream: The BBC iPlayer, BBC Sport website and S4C online (all free with a subscription) will offer live streams for fans online.
LIVE coverage: Follow all the action with Standard Sport’s dedicated match blog. Malik Ouzia will be providing expert analysis from the Ahmad bin Ali Stadium in Al Rayyan.