Northern Ireland's footballers are likely to wear black armbands against Germany in memory of a fan who died during their win over Ukraine.
obert "Archie" Rainey suffered a fatal heart attack as he watched Thursday's game in Lyon. His family said he died "doing what he loved best".
Northern Ireland boss Michael O'Neill also spoke of his sadness.
It is the second tragedy to rock the team's Euro 2016 campaign, following the death of 24-year-old Darren Rodgers in Nice.
Tributes were paid to Darren during the Ukraine game - and similar are planned for Mr Rainey at the Parc des Princes in Paris on Tuesday.
The Irish Football Association has asked Uefa for permission for the players to wear black armbands.
It said: "As a mark of respect for the late Robert Rainey, the Irish FA will request that the Northern Ireland players wear black armbands for the game against Germany in Paris on Tuesday night."
Mr O'Neill added: "We were all shocked when we heard this sad news after the game.
"The thoughts of all the players and the backroom staff are with Robert's family and friends at this time."
Fans are expected to pay their own tribute during Tuesday's game. Supporters at Thursday's match who learned of the tragedy before they left placed shirts, scarves and flags in the stand in Mr Rainey's memory.
Mr Rainey was aged 62 and from Belfast. A statement released by his family said: "The family wish to confirm the sad news that our father Robert Rainey, known to everyone as Archie, sadly passed away whilst in France supporting Northern Ireland at the Euros, surrounded by all his friends and family, doing what he loved best.
"We are obviously devastated at this loss and thankful for everyone's thoughts and prayers. We would appreciate privacy at this sensitive time."
Mr Rainey took ill around 50 minutes into the game at the Stade de Lyon. He had been watching the match with his brother, Brian, and a group of his friends.
Northern Ireland fans who saw him collapse went to his aid.
Maurice Dickson, originally from Belfast, saw the tragedy unfold. "It was quite a distressing thing to see, particularly coming so quickly after Darren Rodgers passed away as well," he said.
Mr Dickson (53), who now lives in Manchester, recalled seeing someone calling to a steward for help and said it was clear the man was in distress.
"There (must have been) a couple of paramedics or doctors amongst the Northern Ireland supporters because they stepped up over seats past us to get up there, and then the medical team in the stadium came running up the stairs," he explained.
"They must have worked on the gentleman for 10 to 15 minutes."
He added: "They worked on him for quite a while and had a defibrillator brought up.
"Shortly after that, the stewards were holding up blankets and some other stewards moved the supporters to other seats. They held up blankets because unfortunately the gentleman had passed away."
Mr Rainey was involved with 92nd Belfast Boys' Brigade.
Its captain David Phillips said: "Archie was a character who will live on in the memories of all of us who had the pleasure to know him. We send our heartfelt sympathy to the family.
"It is comforting to know that he was with his brother, Brian and a group of his friends, many of them 92nd boys, enjoying a great game of football and no doubt great craic."
The Amalgamation of Official Northern Ireland Supporters' Clubs said it was deeply saddened and shocked by the latest tragedy. Its chairman, Gary McAllister, added: "We're devastated that a second fan has lost their life in France this week.
"Our thoughts are with his family and friends at what is a very difficult time for them."
A crowdfunding page has been set up to help raise money to repatriate Mr Rainey's body.
Yesterday, it had passed its £400 target within hours.
Mr Rainey's death overshadowed what had been one of the great nights for Northern Ireland football.
The team beat Ukraine to record its first tournament win since the 1982 World Cup.
After the game, several Northern Ireland players spoke of their shock at the development.
Captain Steven Davis said: "It is terrible news and we'd like to send our condolences and deepest sympathies to his family and friends."
And striker Kyle Lafferty added: "We can't believe it that another of our fans - our brothers - has died.
"We would just like to say we are truly sorry and pay our respects to him. Our sympathies go to his family."
IFA chief executive Patrick Nelson said: "This puts any result of a football match into perspective.
"The thoughts of the board, management, players and staff are with his family and friends at this sad time."
The Football Association of Ireland also paid tribute.
Chief executive John Delaney said it was "a sad outcome to what was a historic day for Northern Irish football".