When Sir Alex Ferguson signed Robin van Persie, there was an element of concern that he was ignoring the areas that really needed an upgrade. The defence was one of those things.
Although Van Persie has gone on to justify the manager's bid for him, the defence continues to be a worry. United have conceded 28 goals already this season, compared to 33 for the entirety of the 2011/12 campaign.
United lost the title on goal difference last year, so Ferguson bought Van Persie. The downside of this was that, despite his goals, the deteriorating defensive record will drag their goal difference down in a repeat situation this year.
Ferguson must act soon to rectify the issue and below are three players who would help him do just that.
A former Red Devil himself, Ferguson sold Shawcross to Stoke for £1 million four years ago and now wishes he hadn't. In an act of prescience, however, a buy-back clause was inserted into his contract that gives United first refusal if he is to be sold on.
Shawcross is reportedly in discussion with Stoke about a six-year contract to ward off potential buyers.
Who would be the best buy for Manchester United?
Shawcross has proven himself as a defensive leader and would give the United defence an extra level of grit. Stoke have kept nine clean sheets this year and Ferguson has to be envious of that.
The pre-existing history between club and player could work both ways here. Does Shawcross want to leave regular first-team football for a bigger club and a lesser role, or does he take his chances and rely on that relationship to force his way into the side?
According to the Daily Mirror, Ferguson will make a move for Okore in January. Aged just 20, the Danish international would make an ideal long-term replacement for Rio Ferdinand.
Okore provides a strong aerial presence as well as strong tackling and a solid passing game. His value will only increase as he gets more opportunities, but he is unlikely to stay at FC Nordsjaelland for very long.
The Danish side have suffered a series of heavy defeats at the hands of superior opposition—Chelsea beat them 6-1—but Okore is one of the nation's brightest young defenders and United would get a very promising prospect.
Okore already reads the game well and possesses excellent instincts and close control, so the pace of the EPL is unlikely to trouble him.
If Ferdinand was to be offered a one-year deal after this season, Okore could learn behind him and get acquainted with the English game through the smaller fixtures.
It's certainly an exciting proposition, and with SkySports.com estimating his value at £3 million, one that comes at incredibly good value.
Manchester United old boy Ole Gunnar Solskjaer would be disappointed to see his prize defensive asset leave, but Forren can't be expected to remain at FC Molde forever.
They'd lose, for one thing.
Forren plays with a style that's easy to admire, mixing well-timed sliding tackles with the composure to stay on his feet and play the ball out of defence. He has an elegance in possession that isn't seen with a lot of defenders.
His ability in the air is bound to attract Ferguson, as he has excellent timing when going up for an aerial challenge. At 6'1”, he isn't the tallest defender in the world, but he has obviously worked hard to make the most of his height by combining it with great technical ability.
He is also just 24, so he would be at United long enough to become a long-term fixture at the back. Don't be surprised to see him linked with United a lot more as the deadline approaches.