The anthem could get an icy response in Cardiff because of the Football Association of Wales' opposition to the idea of a British team, which it shares with the Scots and Northern Irish who fear the concept may erode their independence within FIFA, world football's governing body.
Many Welsh, Irish and Scottish fans feel the same way. The four parts of the United Kingdom, including England, compete as individual teams in non-Olympic international football.
Any snub of the song before the match in Wales would embarrass Britain's Olympic organisers who put Queen Elizabeth at the heart of Friday's opening ceremony with a virtuoso role as a "Bond girl" alongside James Bond actor Daniel Craig.
Some Welsh players, including Giggs, did not sing "God Save The Queen" before Sunday's game or against Senegal in their opening match on Thursday.
Cardiff-born Giggs, who scored the opening goal in Britain's 3-1 win over the United Arab Emirates on Sunday, hopes Welsh fans don't boo the song even though, in a somewhat convoluted explanation, he said he did not to sing it for personal reasons.
"It's a personal thing. The British anthem is the same for a Welshman, Scotsman or an Englishman," he said.
"It's difficult but it's not an issue for us. It might be for other people but, once the game starts, we're all pulling in the same direction and I think that's the main thing.
"I hope it won't get booed and I hope the fans will get behind us as they have in our first two games."
RECORD BREAKER
Giggs, who on Sunday became the oldest player to score in Olympic football, was one of five Welsh players in the starting line up as Britain took a significant step towards the quarter finals.
They will secure their place in the last eight as long as they avoid defeat against Uruguay, who surprisingly lost 2-0 to Senegal in the first match of Sunday's double-header at Wembley.
"It will mean a lot to all of the Welsh lads to play in our own stadium, our own back yard, so it will be a great occasion," Giggs said.
The Welshman broke an 88-year-old record by scoring at the age of 38 years and 243 days on Sunday. He also became the oldest man to play in the tournament.
After his goal, the United Arab Emirates equalised before substitute Scott Sinclair scored with his first touch and fellow sub Daniel Sturridge made it 3-1 to Britain with a superb chip.
Giggs continued: "It was a very important win, especially after the Senegal result and the pressure was on.
"I'm still disappointed not to play in a World Cup, a Euros or a major tournament and now this is something I'm relishing.'
Manager Stuart Pearce added: "I've been absolutely delighted with the support we've had, certainly in numbers, at Manchester and at Wembley. I think that will continue again in Cardiff.
"I was told this is somewhere in the region of the biggest attendance of an Olympic football match there's ever been. That sends a message out straight away.
