Inside the City of Manchester Stadium on a cold October night, spectators just about outnumbered the empty seats. Those that had made it out sat in mostly quiet observance, and as the warmth inside the ground ebbed away slowly over 90 minutes, so did any spark of atmosphere. Man City against Arsenal in 2004 was not Man City against Arsenal in 2018. The 2004/05 Carling Cup third-round tie was played without fanfare, a reminder, if one was needed, of the inertia that had washed over both the competition and the home team. But it’s clear now that the game took place at the beginning of a giant, irreversible shift in English football. Man City fans were still three years from the mammoth investments that would see their club transformed. But at the other end of the pitch, the country’s dominant team had already started to crack. Three days earlier, just a few miles across town, Premier League champions Arsenal had lost 2-0 to Man Utd at Old Trafford, a first defeat in 49 league games. It would be a symbolic changing of the guard, the beginning of a sudden and unexpected end to what most had assumed would become a dynasty. Arsene Wenger, who months earlier had been promised ‘a job for life’ by Arsenal chairman Peter Hill-Wood, had penned a new contract the previous week, and following the United defeat felt confident enough to change his entire XI, bringing in an unrecognized team of young players and academy graduates for the game at City. Every member of the starting team was under 21 years old. Three were just 17. Yet City, pre-Abu Dhabi billions, were outclassed, beaten 2-1 on their own patch by a group of players with barely a Premier League appearance between them. Arsenal’s second string played with the same slickness and ease as their senior colleagues, batting City’s elders to one side with confidence and sass. Not that everyone was impressed. "Embarrassed is the word for it," said City's manager Kevin Keegan afterwards. "Don't take anything away from them, but we've been beaten by a few fringe players and Arsenal's third XI.” Three weeks later, those same fringe players beat Everton’s seniors 3-1 at Highbury. That this team would go on to inherit the glorious mantle of Arsenal’s Invincibles seemed without doubt. “We were the best youth team in the country at the time,” says Jermaine Pennant, who started for Arsenal on the right wing at the City of Manchester Stadium. “But in those days, the young players didn’t really get a chance at Arsenal. It wasn’t the club’s kind of thing.”