It's no secret that Manchester United are struggling for scoring form under Louis van Gaal, £36 million man Anthony Martial has only scored six goals in 18 games for United, while Wayne Rooney hasn't hit his goalscoring form of previous years.
Despite this, United are sitting in fourth place in the Premier League. Here are five players that could see the Red Devils challenge for the title:
5. Ilkay Gundogan - Borussia Dortmund
The German international has been linked to Louis van Gaal's side in previous years, however, United have failed to win his signature.
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Gundogan's creativity and vision is something that United lack, despite signing midfielders Bastian Schweinsteiger and Morgan Schneiderlin in the summer.
Should United have another go at winning the German's signature, they need to act fast, as Gundogan has attracted interest from major clubs all across Europe.
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4. Sadio Mane - Southampton
A player who was rumoured to be the subject of a £28 million bid from United over the summer, Mane has shone for the Saints this season picking up seven goals, including a valuable late equaliser at Anfield. Ronald Koeman has since said that he wouldn't sell the attacking midfielder for £100 million. Will the Red Devils make another surge for the Senegal international?
3. Neymar - Barcelona
Perhaps not a realistic target for United, but it has been confirmed that United made an approach towards Neymar. Some have suggested that Neymar is unsettled in Catalonia, but that hasn't stopped him winning a place in the final three for the Ballon d'Or in January. The Brazilian is arguably the world's hottest footballing prospect, but a move to United would be seen as a step down.
2. Cristiano Ronaldo - Real Madrid
Every single season we hear rumours about a return to Old Trafford for the three-time Ballon d'Or winner. But it really seems like a possibility now, with Sky Sports' Guillem Balague stating that both Ronaldo and manager Rafael Benitez will not be at the Bernabeu next season.
Could this hint at a sensational return for Ronaldo? Some argue that the Portuguese international is past his peak, however, you can't deny his skill and prowess.
1. Pierre-Emerick Aubameyang - Borussia Dortmund
Possibly a surprising top pick for many, this prolific striker has helped Dortmund back to the big time in the Bundesliga. The Gabon international has netted 22 goals in 19 games for Dortmund, surpassing Manchester United's total Premier League goal tally of 20.
Aubameyang would add much-needed pace to United's front line. Once again, he is a target for many European clubs, so the Red Devils need to act swiftly in January.
Manchester United fans - who do you think your club should sign? Give your opinion in the comment box below!