It looks like the two Premier League clubs will be the main ones to compete for the Uruguayan's signature, and while Chelsea have made official contact with Napoli over a move, City are the slight favourites at present.
What could prove crucial is that it's widely believed that Napoli and new boss Rafael Benitez want City's Edin Dzeko as a replacement, so either a swap deal or an agreement to transfer both could be on the cards, giving City an extra bargaining chip.
Verdict: Near-certain to go to one or the other, but too close to say which.
This one seemed highly fanciful when it first dropped, but it appears that at the very least, United believe they're in with a shout. ESPN have reported that the Red Devils are serious,with the intent to make a "statement signing" if Wayne Rooney, as seems likely, leaves the club.
Also reported is that a bid of over £25m would be enough to sign the midfielder, which could be very good business for United. The question, then, is how much Fabregas wants it - there's no suggestion he's desperate to move, and other sources reported he's told United he wants to stay at Barcelona.
Verdict: Probably unlikely, but certainly possible.
Thiago Alcantara to Manchester United
This one is certainly more likely. With Thiago having a clause in his contract that stated his release clause would drop to just 18m Euros for this transfer window should he fail to play in less than 60% of games in the last season, it's probably now or never for Manchester United. And it looks like 'now' is the more likely.
Although probably not as good a fit as Fabregas, since it's doubtful how well he'd function in a midfield two, getting a supremely talented player for such a low price is perhaps a no-brainer for the Red Devils, especially if they miss out on Fabregas. With United's midfield rather easier to get a place in than Barcelona's, the attraction for the player is obvious.
Verdict: Likely. United tried to get him before, and have a golden opportunity to secure his signing now.
Marouane Fellaini to Manchester United
The third of the big United midfield options. Although moved into a more advanced role in the past season, Fellaini's preferred role is deeper in midfield, where United are crying out for some physicality and steel. It would certainly suit the Red Devils, and we can pretty much assure ourselves that David Moyes is a fan.
As for the player, he's recently been giving interviews where he's very thinly disguised his desire to make such a move - discussing how he'd only move for a manager that trusted him in one sentence and talking up David Moyes immediately afterwards. If United want to get it done, there will be no complications.
Verdict: Potentially very likely. It all rests on how keen United are.
It's no secret that Tottenham want a new striker, possibly two, and London's Evening Standard reports that talks between Spurs and Barcelona are at an advanced stage over a move for David Villa.
Villa could certainly add class to Tottenham's forward line, although they would have to make him one of the highest-paid players at the club to do so. That may be purely a one-off consideration however, since the club will likely have to adjust their wage structure once again if Gareth Bale signs a new contract.
Verdict: This actually looks likely. As with all transfers that would've been inconceivable a couple of years back, it'll be either a roaring success or a disastrous failure, but it looks like it's going to happen.
Jackson Martinez to Tottenham Hotspur
Spurs may be after two strikers this summer, and while we can expect the lengthy Leandro Damiao courtship to be renewed, it's been suggested that Spurs will also look into getting Jackson Martinez from Andre Villas-Boas' old club, Porto.
The biggest sticking point would surely be Porto's reluctance to let him go, however - they're a selling club, and have built their model around it, but they've already got rid of James Rodriguez and Joao Moutinho this summer, and are unlikely to have reason or desire to lose their best striker in the same summer.
Verdict: Highly unlikely that Porto would consider a sale. Come back next year.
Stevan Jovetic to Arsenal
A suggestion that looked to make a lot of sense if the rumours about Arsenal having a big summer were true, but reports suggest the Gunners are now unwilling to pay full price for the striker.
It would be typical Arsenal if so, and Chelsea are also rumoured to have an interest, with Juventus very much in the picture too. Arsenal may be spending big this summer, but they're highly unlikely to win any bidding war with those two.
Verdict: Possible if interest from elsewhere cools, but looking increasingly unlikely.
Gonzalo Higuain to Arsenal
A transfer that's been mooted before, and now far more likely with the Argentine almost certain to leave Real Madrid. The problem is that the situation is almost identical to the Jovetic scenario, with plenty of other teams also looking for strikers. Monaco and Juventus are likely to be two obstacles in getting this deal done.
Verdict: Same as Jovetic - possible, but hard to see Arsenal winning any bidding wars with player or club. He is on very low wages, however, so if his other suitors see him more as a cheap option, then it could be done.