Messi made it clear to Barcelona that he wanted to leave the club but his contract and buyout clause made any move impossible.
The Argentine was forced to stay as a result but has remained unhappy with the direction of the club and his contract expires next summer, with no indication that he will sign an extension.
This has kept Manchester City in the picture and despite the release clause of £700m still in place in the January window, Barcelona may be enticed by a reasonable offer.
The Catalan giants are in dire straits financially, with the coronavirus crisis increasing their debt to £750m as they sought desperately to get players off the books, including Luis Suarez.
Messi remains by far the highest earner and a modest transfer offer that earns Barcelona a fee and also frees them from the 33-year-old's salary could be enticing and something they are forced to accept.
Messi and Barcelona suffered their first defeat of the season Saturday, going down 1-0 to a well-drilled Getafe side in Madrid.