The Brazilian superstar has been a key member of the Catalan giants’ first-team set-up for some time, but rumours have begun to circulate that his time at the club is coming to an end.
Alves’ current contract expires at the end of next season, and with talk of a falling out between the player and other personnel and the Nou Camp he is thought to be available.
There are few teams on the planet that can realistically afford a deal for the rampaging South American, but City and United are two that can fund a big offer.
Both teams are believed to be on the lookout for defensive reinforcements, with the Red Devils in particular need of a right-sided option.
David Moyes is known to have a vast budget as his disposal, and could use some of it to secure Alves – who would be seen as an upgrade on current first choice Rafael.
City possess Pablo Zabaleta, but with the Argentine also capable on the opposite flank the current Barca man would offer more attacking intent.