What will it cost to sign Liverpool winger Raheem Sterling this summer?

Manchester City have started the bidding in what threatens to be one of the most protracted transfers of the summer, offering £25m, plus add-ons, for Liverpool's Raheem Sterling. A summer transfer seems inevitable for the 20-year-old after he rejected Liverpool's £100,000-a-week contract and, via his agent, made it clear he would turn down any follow-up offer too, even it was worth "£900,000 a week".

Manchester CIty's bid comes a day after City chairman Khaldoon Al Mubarak pledged to invest in players and Sterling seems to be at the heart of their plans. Liverpool know that Manchester City can afford to pay more than £25m and with Arsenal, Manchester United and Real Madrid also linked, City may now trigger an auction. But how much can Liverpool really expect to get for the forward?

Suggestions are that the Reds value Sterling at around £50m, but does their recent contract offer to him really reflect that? With new signing James Milner thought to be on something approaching £150,000-a-week for the next four years, should the Reds have been more generous with Sterling - if only to show how highly they rate him? Equally, has Sterling really shown the potential to command a fee that would make him one of the most expensive transfers of all time?

Perhaps the most extraordinary thing about Sterling is the amount of games he has played at his tender age. After making his breakthrough at the end of the 2011-12 season, the winger has played 124 times for the club. To give a comparison, that's the same number of games that Arsenal's Abou Diaby has managed in the Premier League in nine years. He's suffered very few injuries and, despite being criticised for having a week's holiday when Liverpool played Sunderland, featured in 52 out of the club's 58 games last season. Suffering so few injuries at his age has to be a positive sign.

Sterling's seven Premier League goals last season compare favourably to Manchester City's current wide players, comprehensively beating Jesus Navas' zero and Samir Nasri's two. For assists he stands equal with David Silva on seven, one better than Nasri (although the Frenchman played fewer games), and one behind Navas. Where Sterling really stands out is with his dribbling, attempting an extraordinary 233 dribbles last season which is more than James Milner, Samir Nasri, Jesus Navas and David Silva combined. That said, his dribble completion is relatively low at 44% so there is room for improvement in the 20-year-old's decision making.

What's clear is that Sterling could improve a top four side right now, while having the potential to get better. There aren't too many players who are available who fall into both of those categories, which is why Liverpool will demand a premium. To back up their demands, the football observatory's independent report on player values judged Sterling to be worth around €75m (£54m) so perhaps Liverpool's judgment is fair. The counter argument is that the player has made his dissatisfaction so public that it damages Liverpool's bargaining position and there is, of course, still an element of risk about Sterling's future development.

All told, Liverpool are unlikely to get the £50m figure that they've made public but they will be able to drive the price up significantly. Perhaps an offer of £40,000,001 would do the business this time.

Neil Custis (The Sun): "Raheem Sterling is not worth £50m. If Angel Di Maria was worth just over that, having proved himself at the highest level in Champions League finals and World Cups, how can Sterling come close? I would think £30m is about right.”

Daniel Taylor and Dominic Fifield (The Guardian): "Liverpool are expected to relax that position if a much higher bid comes in now it is absolutely clear Sterling is determined to leave and has an agent, Aidy Ward, who is willing to embroil himself in a public dispute with the club to help get what he and the player want. However, the likelihood is that City would have to make a substantially larger offer."

Michael Owen (BT Sport): "If Liverpool lose Sterling, they can replace him with the money you get. He’s a very good player with lots of potential, but you can replace him. If I was a Liverpool fan, I’d obviously be wanting an answer [as to whether Sterling will stay or go] but I wouldn’t be losing sleep if he did leave and you got a fair old chunk of money for him.”