When Manchester City began their ascent, backed with a budget to rival the richest around, Sir Alex Ferguson tried not to let it faze him.
The Manchester United boss made reference to the "noisy neighbours" from across town while his own team remained the bigger players, reaching the Champions League final in 2009 and 2011 and winning the league in both of those seasons. However, there were moments where he struggled to hide his true feelings, and the arrival of Carlos Tevez at the City of Manchester Stadium was one of them.
Tevez had been a prime example of Fergie getting his man, with United winning the race to sign the Argentina star after a year spent adapting to English football with West Ham United. However, as the forward opted to cross the city and sign for the neighbours, we got a sense of what was really at stake.
Ferguson attempted to brush some of it off, especially when the infamous "Welcome to Manchester" banner was erected in the centre of the city. However, with United also losing Cristiano Ronaldo to Real Madrid that same summer, the efforts to save face may have been necessary.
"The billboard in Manchester is just City all over, isn't it?" the manager said at the time. "They are a small club with a small mentality and all they can talk about is Manchester United.
"That's all they've done and they can't get away from it. The poster is a stupid thing using Tevez in that way and they've shown an arrogance which does them no favours.
"It's clear that it's a go at us because they think taking Tevez away from Manchester United is a triumph. But it's poor stuff."
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"City showed me their ambition to be one of the biggest clubs in the world and I was happy to join," said Tevez, who had turned down an approach to stay with United. City had finished the previous season in mid-table, increasing the pressure on manager Mark Hughes, but Tevez's impact was an instant one with four straight wins to kick off the season.
The Argentine scored his first goal for City in the League Cup, and opened his account in the league in September in a victory over West Ham which made it five wins from six. However, the other game in that run saw Hughes' side beaten at Old Trafford thanks to Michael Owen's last-gasp winner, leaving Fergie with the upper hand for the time being at least.
Still, the animosity seemed to remain. "When I asked him about the poster on United's tour of the Far East that summer, he later approached me to ask why they had done it," the Sunday Mirror's Simon Mullock would later recall.
"'To get under United's skin,' I said. 'And it looks like it's worked.'"
Ferguson himself, meanwhile, would insist on having the last word even after both he and Tevez had left their Manchester clubs. In an extract from his book, he made it clear the valuation of Tevez - coupled with a price tag once reported as £47m but argued by others to be lower - was out of sync with his own views on the player.
"I brought Tevez on at half-time [in the 2009 Champions League final] and just felt he was playing for himself a little bit," Ferguson wrote. "From what I could gather, he had already made his mind up before joining City.
“The rumour, not confirmed, was that our Manchester rivals had paid £47million. To me these were incredible sums. To me he was an impact player.”
Tevez ended that first Manchester City season with 23 league goals, a tally he would never better in a long and illustrious career. And yet it wasn't enough for a top four finish, with Hughes' time running out in December and Roberto Mancini missing out on Champions League football thanks to a defeat against Tottenham Hotspur in May.
It was under the guidance of the Italian that City eventually ended their wait for a Premier League title, and with it went some way to silencing the United manager. And it was also the source of another controversial banner, albeit one which took far less planning.
After returning from some time on the sidelines to help City win the title in 2011-12, Tevez got involved in the parade held to mark the occasion. It was there that he was handed a banner which - as we would soon learn - carried the distasteful message 'RIP Fergie'.
"I got carried away in the excitement of the moment and I certainly didn't mean any disrespect to Sir Alex Ferguson, who I admire as a man and a manager," Tevez said. City themselves also apologised for what they admitted was "tasteless material".
Later, though, the Argentine would speak further on the matter, declining the option to leave it all in the past. "It seems like Ferguson is the President of England," he told Ole.
"Because every time he speaks badly of a player or when he always talked rubbish about me, I never went out to say he had to apologise. When you mess up you should go out and apologise, but I do not apologise."
Some 13 years on from Tevez's move, United are very much second in line as far as the Manchester clubs are concerned. City have won five league titles since United's most recent one in 2013, and continue to beat their neighbours to signings - Erling Haaland being just one of the more recent examples.
The Tevez move might have been used by an angered Ferguson to take aim at his team's rivals. However, if the anger was borne out of fear for what City might grow into, it would be hard to argue those fears haven't been realised.
