Arsenal say their position on Alexis Sánchez is unchanged – the striker is not for sale – after Manchester City finally moved for their long-time target with a straight cash offer of £50m.

Ferran Soriano, the City chief executive, spoke to his Arsenal counterpart, Ivan Gazidis, on Tuesday and after weeks of dancing around he put forward the official bid. It was not to alter Arsenal’s resolve over the player.

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They are determined to hold Sánchez to the final year of his contract, even though he has made it clear he will not sign a new one and, as such, would stand to leave for nothing next summer. Moreover, it is his preference to join City before the transfer deadline on Thursday. Arsenal continue to believe he would apply himself in their colours after 1 September and give his best for one last season.

The situation is delicate and complex and there is the acceptance at Arsenal that every player has his price – even Sánchez, who is undeniably the club’s biggest star. Were City to come back with an offer that located the tipping point, the saga could twist again. City have the time to do so before deadline. But, as things stand, that has not happened.

Arsenal have had an interest in the Monaco attacking midfielder Thomas Lemar throughout the summer – Liverpool are also now in for him – but the French club have indicated it would cost €80m (£74m) to get him. In other words he is not for sale. It is safe to assume Arsenal’s tipping point for Sánchez would, at the very least, be equal to this figure.

During the conversation between Soriano and Gazidis, the City forward Raheem Sterling emerged as a potential makeweight in the deal for Sánchez. City contend it was not Soriano who suggested this. The club went to great lengths to prise Sterling from Liverpool for £49m in 2015 and he has started the season with vital goals against Everton and Bournemouth. But it is unclear whether Pep Guardiola counts on him. Mixing players into deals is notoriously complicated and City would prefer a straight cash transaction for Sánchez.

Arsenal know that selling their best player to City and, in effect, getting an unwanted one back from Guardiola would not wash with their supporters. Perhaps, if they could add Lemar as well, it would be more palatable. But they are acutely aware of the difficulties, at this late stage, of the practicalities of getting a replacement or replacements for Sánchez.

The 28-year-old is in Chile preparing for his World Cup qualifier against Paraguay on Thursday. Were there to be a breakthrough over his move, City would get a doctor out to him to supervise the medical.

Arsenal are interested in the West Bromwich Albion centre-half Jonny Evans, who is also wanted by Manchester City and Leicester City, as they consider whether to move Shkodran Mustafi out to Internazionale. Mustafi wants to leave Arsenal. The club are also in talks with West Brom about selling Kieran Gibbs to them for £7m. Alex Oxlade-Chamberlain is primed to complete his £40m switch to Chelsea.

City have a potential problem over Sergio Agüero, with the feeling within the club being that the Argentina striker might pursue a move away in January. He was dropped by Guardiola for the Premier League win at Bournemouth on Saturday and there has been tension between the player and manager. Agüero is determined to play regularly in World Cup year.