Christian Pulisic was decisive as the United States beat Iran 1-0 to secure their place in the last 16 of the World Cup as geopolitics briefly took a back seat at Al Thumama Stadium.

Due to the long-strained relationship between the two countries politically and the ongoing civil unrest in Iran, the build-up to Tuesday's Group B clash was dominated by talk of almost anything but football.

Once the game settled, however, the USA's superiority was abundantly clear and Iran were fortunate to only trail by Pulisic's goal at the break, with Timothy Weah having one disallowed.

Carlos Queiroz's side did at least manage a shot after the break, but the USA had enough to see out a slender – albeit deserved – victory and set up a last-16 clash with Group A winners the Netherlands.

After an emotionally charged opening that saw both sides show purpose, the USA began to probe with the greater regularity.

Weah let Iran off the hook just before the half-hour, taking an early header – which led to an easy save – unaware he had time for the ball to drop.

Pulisic gave Alireza Beiranvand no chance 10 minutes later, though.

Sergino Dest headed Weston McKennie's exquisite pass into the danger zone and Pulisic slammed home while colliding with Beiranvand, ultimately forcing the Chelsea man off at the interval.

Weah strayed just offside before scoring what he thought was the USA's second, and half-time substitute Saman Ghoddos almost capitalised as he headed over just after the break.

Iran enjoyed a lot of late pressure but their efforts did not yield an equaliser, with Morteza Pouraliganji heading agonisingly wide and Mehdi Taremi failing to convert from close range in stoppage time.