The Premier League champions have coveted the Argentina international for over a decade but he has been untouchable for years.
But recent unrest between the six-time Ballon d’Or winner and Barcelona may have left the door open for a move.
His very public spat with sporting director Eric Abidal, his former team-mate, stemmed from months of frustration at how the club is being run.
This week, when discussing the messy sacking of Ernesto Valverde, Abidal claimed that several players had downed tools but Messi was having none of it and fired back on social media.
Messi wrote on Instagram that he should name names to avoid “throwing dirt at everyone and starting rumours that aren’t true”.
The 32-year-old has a clause in his £57m-a-year contract allows him to leave on a free transfer this summer if he pleases.
And City are ready to pounce even though they know that signing him is still unlikely.
Officially, the Premier League side insist there is no chance of Messi signing for them but deep down they believe Messi may be ready to trigger his release clause, according to The Athletic.
It has been reported that the clause applies only to non-European clubs, but it applies to any club and City are aware of that.
Messi, if he wanted to, could leave this summer if he communicates his decision to Barcelona before the end of May.
The clause is valid at the end of every season until June 30, as it has been since he signed the agreement in 2017.
City boss Pep Guardiola has always said that Messi should end his career with Barcelona.
But the forward personally called Pep before his first season at City to make it clear that he wanted to play under him again.
The pair won 14 trophies together at Barcelona in a four year spell, playing arguably the best club football ever seen.
City have fallen well off the pace in the Premier League this season with Liverpool running away with the title.
Signing Messi this summer would certainly put the cat amongst the pigeons at Anfield and elsewhere in the English top flight.