It's a game of very fine margins
Iranian football fans have spent several hours overnight outside the Portugal team's hotel in Russia making noise in an attempt to prevent the players from sleeping.
The two countries meet later on today in their final group game of the World Cup, and Iran could still go through if they beat Portugal this evening. Portugal just need a point to go through to the knockout rounds, as they sit one point ahead of Iran going into the final game.
Portuguese TV station RTP broadcast footage of Cristiano Ronaldo gesturing to the Iran fans, asking them to make less noise.
Iranian fans reportedly spread messages on social media asking more fans to come down and participate in their disruptive tactics.
At elite level, football is a game of fine margins. If Iran come away with a victory, the fans will feel that they played a big part in the team's success.
