The Senegal international could be the addition that sends Louis van Gaal's side back towards the league crown.
Sadio Mane has been on Manchester United's radar since the summer, according to the Telegraph, so it is no surprise that his name is being linked with a January switch to Old Trafford once again. According to the Daily Mail, the Red Devils are hoping to tempt the Senegal international away during the upcoming window, and while Southampton are defiant that a move will not be happening, the Mail suggest that there are growing fears around the club that their star's departure is inevitable.
While the Mail claim that a deal at the end of the season seems more likely, Louis van Gaal knows that with United nicely poised in the Premier League, signing Mane midway through the season may be the move that propels the club back to the summit of the top-flight.
After a very busy summer, and a promising start to the season, it seems unlikely that the Dutchman will seek to make huge changes to a squad that is only being kept off top spot by Leicester City. While the Foxes have stunned everyone during this campaign, a few injuries to key players may well expose the lack of depth that exists in Claudio Ranieri's squad, and should see them finally slide down the table.
With the Red Devils grinding out positive results, and building a defence that has become very difficult to break down - Watford's penalty on Saturday ended the club's run of five successive clean sheets in all competitions - the addition of an exciting winger is all that is stopping the club from ending their wait for the title.
Mane has proved during his time on the south coast that he is capable of making the step up to a club that currently considers itself a top-four favourite. United's lack of depth on both the wing and up front makes the 23-year-old an obvious signing.
His pace and trickery has made him one of the main players that defenders hate coming up against. He has already booked a place in Premier League history by eclipsing Robbie Fowler's record for the fastest hat-trick when his treble sank Aston Villa last season.
And while some at St Mary's may have been concerned that his form would dip in his second campaign, he has largely picked up where he left off. He has already found the back of the net at Anfield and was instrumental in the Saints' dismantling of Chelsea last month.
While United would probably have to make something of an inflated offer to sign the former Red Bull Salzburg man - such is his worth to Ronald Koeman's side - there are few players that boast Premier League experience and are still young enough to grow immensely having already demonstrated on so many occasions that they can tear defenders apart.
With van Gaal's squad looking strong, the addition of Mane's creative flair, as well as his ability to know when to be selfish and when to take an opportunity on himself, would make him the signing that could confirm United's return to the top.