DOHA - The United States and Iran meet in a politically charged winner-takes-all World Cup clash on Tuesday as England aim to reach the last 16 as group winners with victory over Wales.
Ever since the draw for the tournament was made in April, the Group B game between the US and Iran has stood out as one of the highlights of the first phase in Qatar.
Even with little riding on the result, the game at Al Thumama Stadium would have been loaded with political overtones, only the third meeting on a football field of two nations who share more than 40 years of ideological enmity.
But Tuesday's match carries an additional dimension with both teams knowing that a win will see one of them advance to the knockout rounds while the loser is eliminated.
As if that wasn't enough, simmering tensions flared up at the weekend after the US Soccer federation posted a modified version of the Iranian flag on their social media feeds.
The move infuriated Iranian football chiefs, who lodged a complaint with FIFA demanding sanctions.
US Soccer initially said the altered flag, with the word Allah removed, was intended to show support for women protesters in Iran, before it subsequently deleting the various posts.
Coach Gregg Berhalter said on Monday his players and team staff had been in the dark about his federation's flag gesture and sought to emphasise that politics would not be a factor.
"When I think about this match I know that a lot of other constituents have a lot of other feelings towards it," Berhalter said.
"But for us it's a soccer game against a good team and it's not much more than that. It's a knockout game between two good teams that want to get to the next round."
Iran counterpart Carlos Queiroz brushed off suggestions that he would use the flag furore to motivate his players.
"If after 42 years in this game as a coach I still believe I can win games with those mental games, I think I've learned nothing about the game," the Portuguese coach said.
US Secretary of State Antony Blinken said he hoped the players would be allowed to "do their thing".
"I don't think there are any particular geopolitical aspects to this other than that. We have what should be a competitive game and let's let the game speak for itself," Blinken said at a NATO foreign ministers meeting in Bucharest.
- Wales need miracle
In Tuesday's other Group B game England will be looking for a win over Wales as they bid to qualify for the last 16 as group winners.
England made a flying start to the tournament with a 6-2 demolition of Iran but were then held to a laboured 0-0 draw by the USA.
England manager Gareth Southgate is expected to tweak his starting line-up to rest some of his star men against a Welsh team who need a miracle to qualify.
In other games on Tuesday, the Netherlands face already eliminated hosts Qatar as the Dutch strive to finish top of Group A.
Ecuador, who are level with the Dutch on four points, will finish top of the group if they come up with a better result against Senegal than the Netherlands manage against Qatar.
The winners of Group A will face the runners-up from Group B in the last 16. Failure to top the group could conceivably see the Netherlands face England in the second round.
An Italian man who ran onto the pitch during Monday's game between Portugal and Uruguay carrying a rainbow flag has been released following a brief detention, the Italian foreign ministry said.
The man identified as Mario Ferri also wore a T-shirt with the words "Respect for Iranian Woman" on the back and "Save Ukraine" on the front.
He was on the field for about 30 seconds during Portugal's 2-0 win before being tackled and escorted off by security.
"After a brief detention, he was released by the authorities without any further consequences," the Italian foreign ministry told AFP, without specifying where he was held or by whom.
Ferri said on Instagram: "FIFA banned rainbow captain's armbands and human rights flags in the stands, they blocked everyone, BUT NOT ME."
Ferri has staged similar protests before, including at the 2014 World Cup in Brazil, where he raised the issue of children living in poverty.