7 Possible Transfers to Make Manchester United Top-Four Contenders

Manchester United spent a record £150 million during the summer, but they're still short in key areas as they chase a top-four finish and with it a place in next season's Champions League.

They're still missing a world-class centre-back and a holding midfielder.

It's unlikely Louis van Gaal will be able to solve all of his squad's problems in January. But it's possible he could dip into the market should the right opportunity present itself.

Here's a list of seven players who would aid United's pursuit of a Champions League place.

Kevin Strootman

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According to Tom Hopkinson of the Mirror, Louis van Gaal is a fan of Kevin Strootman, and United are in need of a top-quality midfielder. Van Gaal might have made his move in the summer if the 24-year-old hadn't been recovering from a knee injury.

If his rehabilitation continues as expected, he should return to the Roma team before Christmas. United will monitor his fitness, but he remains the most likely candidate to fill the hole in United's midfield.

Mat Hummels

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Despite the arrival of Marcos Rojo, United are still in need of another centre-back. According to Simon Mullock of the Mirror, Van Gaal was interested in Mats Hummels in the summer, but Borussia Dortmund made no indication they were willing to let him go.

Even when Rojo, Phil Jones, Jonny Evans and Chris Smalling are fit, United still look short at the back. They need a world-class centre-half and Hummels is one of the best around.

Arturo Vidal

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Arturo Vidal's performances for Chile at the World Cup were proof, if any was needed, that he would solve many of United's issues in midfield.

United targeted Vidal over the summer, and speculation surrounding the Chilean is building once again as the January transfer window approaches, according to Aaron Flanagan of the Mirror. 

Vidal would be an asset to Van Gaal as he tries to lead United into the top four this season.

Joao Moutinho

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Van Gaal will have to address the issue in the centre of United's midfield at some stage. Especially if he doesn't fancy Marouane Fellaini.

Ben Jefferson of the Express speculates Joao Moutinho could make a move to United.

He would offer something different to the players Van Gaal already has. But it's debatable whether the Dutchman will want to splash out a player who is already 28 years old.

Raphael Varane

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The fact United still look short at the back when they are at full strength means some fans are surprised that the problem wasn't properly addressed in the summer.

Real Madrid would be reluctant to let a player of Raphael Varane's quality go, and it would certainly be a coup if United could convince him to move to Old Trafford.

There aren't many top centre-halves around. And United are still in need of one.

Neven Subotic

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Like Hummels and Varane, Neven Subotic would fill the hole at the back left by the departures of Rio Ferdinand and Nemanja Vidic.

Adding a player of the 25-year-old Serbian defender's quality would make Van Gaal's options at centre-half look a lot healthier.

Borussia Dortmund wouldn't let him go on the cheap, but he would go some way to solving United's defensive vulnerability.

Cristiano Ronaldo

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United will always be interested in players of Cristiano Ronaldo's quality; the biggest clubs in the world are always interested in the best players.

The question is whether Ronaldo has any desire to return to Old Trafford. He's continued to flirt with the fans ever since his move to the Bernabeu in 2009, but he has nothing left to prove in the Premier League.