By Graham Ruthven (@grahamruthven) For a side of such strength, Manchester City’s title challenge - year-on-year- always seems somewhat fragile. After nearly $1 billion-worth of investment over the past five years or so, the Abu Dhabi-owned side boast some of the best players European soccer can offer, and yet they remain largely reliant on one man: Sergio Aguero. Indeed, the Argentine is the spark from which lights Man City’s flame. Countless millions have been spent on finding an able deputy, or a forward to dovetail with him, but the Etihad Stadium is still the domain of Aguero. Although it won’t be for the next two months or so. In fact, if the player himself is to be believed he will miss City’s next seven fixtures at least having sustained a hamstring injury during Argentina’s World Cup qualifying defeat to Ecuador last week. It’s a development that could derail his club side’s challenge on both domestic and continental fronts. By that measure he will miss matches against Man Utd, Sevilla and maybe even Liverpool, depending on the haste of his recovery. “I hope I can be there against Brazil [on 13 November] but the injury must be let to recover a bit so there is no relapse,” the striker admitted after the World Cup qualifier. “This is an injury you have to recover bit by bit but of course I want to be back quickly.” 

 Of course, Aguero’s injury can only be put down to misfortune for Man City - especially considering how it was sustained with the player on international duty. But it does raise a pertinent question over the composition of Manuel Pellegrini’s side - after so much investment should a team targeting success in the Premier League and in Europe be so dependant on a single player? In simple terms, without Aguero Manchester City are a different team - a significantly poorer team. The Argentine’s recent track record with injuries makes for chequered reading, and precedent shows that with the 27-year-old missing the Citizens struggle to make points stick to the board. Over time Aguero has become the player around which City’s frontline revolves around. Alvaro Negredo, Wilfried Bony, Stevan Jovetic, Edin Dzeko and Mario Balotelli have all been bought - for hefty fees - and yet not one has come close to meeting the standard set by the Argentine. He will forever be a City legend following his now storied last-match, last-minute winner against Queens Park Rangers over three years ago, but Aguero has become much more than just a cult hero in Manchester. While Man City might have opened their chequebook wider than any other side over the past decade or so, Aguero remains their sole truly world-class player. Were soccer to put forward its best eleven players, the Argentine is the only one the Sky Blues could offer.  

  He’s the only one who could hold down a place at a club like Barcelona or Real Madrid - and it’s somewhat surprising neither club has made a serious tilt for his services. Although City would be foolish to sell for any price - Aguero is the embodiment of their grand ambition. Without him their target of one day becoming an elite side and organisation would lose notable credibility. However, the most pressing question to come of Aguero’s injury is: can Man City sustain their challenge both domestically and on the continent without their best player and talisman? Indeed, goals and attacking spark might be hard to come by with the Argentine missing - given City’s lack of suitable replacements. Bony was bought in January as a back-up option but has yet to find his place at his new club, only making a handful of largely low-key appearances from the bench. With Aguero missing Pellegrini might even use Raheem Sterling in a more central position - as Brendan Rodgers often did at Liverpool - such is the lack of options beyond Bony.  Aguero, so many times before, has made the difference for the Etihad Stadium outfit- perhaps even more so in his absence. For the next seven games Man City may have to embark on a programme of damage limitation.