The Iranian team at the World Cup halfheartedly sang its country's national anthem Friday, before beating the team from Wales in Iran's second day of competition in Qatar's Ahmad bin Ali Stadium.
On Friday, boos and jeers met Iran's anthem as the players appeared to merely mouth the lyrics.
Monday's failure of the Iranian athletes to sing the anthem was widely viewed as a demonstration of support for the protests that erupted in Iran after Mehsa Amin, a 22-year-old woman, died in police custody after being detained for not wearing her headscarf properly.
At least four Iranian current and veteran soccer players -- Veria Ghafouri, Hossein Mahini, Parviz Broumand, and Hamidreza Ali Asgari -- have been taken into custody on charges of participating in or supporting the popular protests.
Some of those supporting Iran at Friday's game against Wales were reportedly nationals from countries such as Pakistan and Bangladesh. Some social media users also reported the presence of many non-Iranian spectators, mainly foreign workers living in Qatar, holding the flags of the Islamic Republic.
People wearing clothes with slogans such as 'Freedom Life Woman' or shirts with the name 'Mehsa Amini' were also widely prevented from entering.
"Freedom, Life, Woman" has become a rallying cry for the Iranian demonstrations.