The United States have been dealt a significant injury blow as Christian Pulisic was forced to be substituted at half time.
His 38th-minute finish has given the US one foot into the Round of 16 if they are able to see the victory out against Iran.
The goal was crucial as the Americans are yet to win a game this campaign, having drawn 1-1 with Wales and 0-0 with England.
The Chelsea forward unfortunately injured himself in the process, though, after stretching to connect with the ball and clashing with Iran goalkeeper Alireza Beiranvand.
Pulisic needed if US qualify
Initially, Pulisic carried on but did not return to the pitch after the interval. He has fallen out of favour at Stamford Bridge lately, however, he has been invaluable to his national team in recent years and will be needed in the squad if they secure qualification from the group this evening.