The likes of Carlos Tevez, Owen Hargreaves, Andy Cole and legendary goalkeeper Peter Schmeichel are part of a short list of individuals to have done so.
It’s a rarity, of course, because of the rivalry the two Premier League giants share.
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In doing so, players risk being the subject of hate from the fans of their former employers, yet that doesn’t seem to put them off.
That could well be the case for Victor Valdes soon.
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According to the Guardian, the Citizens are interested in signing the Spaniard, who was released by United last week following a miserable spell at Old Trafford.
City manager Pep Guardiola is reportedly on the lookout for a new goalkeeper and wants to reunite with his former shot-stopper.
The Spanish pair worked together during their days at Barcelona, where they tasted La Liga and Champions League success.
Valdes’ United contract officially expires on June 30, 2016.
Defensive reinforcements appear to be on the agenda for Guardiola but it would appear he’s missed out on a prime summer target.
Aymeric Laporte has frequently been linked with a move to the Etihad in recent weeks, with reports suggesting a £39 million move was in the offing.
However, fresh claims dictate that he has rejected City’s £6.3 million-per-season offer and signed a new deal to stay in Spain worth £4 million-per-year - a club record for Athletic.
As a result, Guardiola’s attentions will likely turn to Everton star John Stones, who is currently on international duty with England at Euro 2016.
The 22-year-old is one of Europe’s highest-rated defenders following a sensational rise to stardom at both domestic and international level.
He is widely regarded as a centre-back cut from the same cloth as Barcelona’s Gerard Pique who, like Stones, is renowned for his ability on the ball, strength and calmness.
Stones isn’t the only Premier League star on City’s radar, though.
Arsenal duo Jack Wilshere and Alex Oxlade-Chamberlain, alongside Tottenham’s Danny Rose, are also reported targets for Guardiola, who wants no less than eight new starters this summer.
And he’s already made one stellar signing in Ilkay Gundogan, who completed a £21 million move from Borussia Dortmund last month.