England's fans created a "special" wall of noise that inspired their team to beat Argentina in their opening World Cup game, according to Ugo Monye.
Steve Borthwick's side won 27-10 in Marseille despite Tom Curry's early sending off.
They had gone into the game below the Pumas in the world rankings following three losses in four warm-up matches.
"I have not heard England fans like that ever," former England wing Monye told the Rugby Union Daily podcast.
"That was really special.
"When I turned up at the stadium, I thought: 'Oh my gosh - the England fans are so outnumbered.' Then in the stadium, I thought there were so many more England fans than Argentines.
"The England players reacted to these fans - they were so loud."
England delivered a clinical performance, in which George Ford scored all 27 of their points - with six penalties and three drop-goals. Ford played at fly-half as a replacement for captain Owen Farrell, banned for a high tackle against Wales in August.
"That was one of the best individual performances seen by an England player in well over a decade," Monye added. "That was his 'I am him' moment."
It was arguably England's best performance since their 2019 World Cup semi-final victory over New Zealand in Japan, with Monye unsure if the atmosphere would have been the same at Twickenham - where England have lost three out of their past four games - following Curry's red card.
"After two and a half minutes when Tom Curry gets sent off, I think Twickenham goes silent," Monye added.
"I do not think England win that match if they play at Twickenham."
'The Rugby World Cup is totally unignorable'
The 10th Rugby World Cup began on Friday with hosts France beating New Zealand 27-13 at Stade de France, with football stars Kylian Mbappe and David Beckham, plus Formula 1's George Russell, all in attendance.
The opening ceremony and the game between two of the tournament favourites attracted the biggest domestic broadcast audience of the year in France as 15.4 million viewers tuned into TF1's coverage.
Alongside France and England's big opening games, South Africa defeated Scotland 18-3 in Marseille in what was a bumper opening weekend of rugby.
"Paris on Friday night was just off the charts great, just in terms of entertainment - speaking about that wider audience," Monye said.
"To go Friday, Saturday and Sunday with three big fixtures in two different stadiums and three incredible atmospheres. But it wasn't just about the stadium, it was about the town and the nation fully coming alive.
"Everywhere you go, the Rugby World Cup is totally unignorable.
"What a life we are living being at the World Cup."