Often the embodiment of the phrase "face like a wet weekend" during his fraught-but-ultimately-successful first season at United, Mourinho has kept up his complaining throughout the summer, moaning that the club have not gotten all of his desired deals over the line.

There were even reports Mourinho was at odds with the Glazer family over slow progress in the market. Hours after such claims surfaced, United have seemingly made a breakthrough. Go figure.

Matic's arrival would placate Mourinho, who is set to be reunited with a player he trusts. Such players tend to thrive in an environment where they have the faith of those in charge, as evidenced by Matic's success enjoyed under the Portuguese, winning the Premier League title with him in 2014-15.

Securing one of the cogs in Chelsea's past two title triumphs, and in a position where United desperately need quality, means a summer that threatened to turn into a damp squib can now be partly salvaged. It seems ludicrous to say United still need to make significant improvements to their squad after spending nearly £600 million since Sir Alex Ferguson retired in 2013, but that is the reality of the situation.

While it's heresy to criticise the greatest football manager of all time, it's fair to say midfield -- specifically centrally -- seemed to be an afterthought towards the end of his 27 years in charge. Marouane Fellaini was the first central midfielder to arrive at Old Trafford in six seasons when he joined under David Moyes in 2013. The last was Owen Hargreaves in 2007-08.

Matic, therefore, would be an important signing. His arrival will, in theory, unshackle Paul Pogba from the defensive burden he had to endure last season and also push midfield terrier Ander Herrera further forward when needed. Having an anchor in front of the back four will protect a defence that performed well in 2016-17 -- only Tottenham conceded fewer in the league -- and it should improve the attack, too.

Matic was the "1" in a 4-1-3-2 at Benfica, although he sometimes had a midfield partner in a 4-2-3-1 before he returned to Chelsea in January 2014, winning two league titles -- the latter of which included forging a strong understanding with N'Golo Kante in Antonio Conte's now-fabled 3-4-3.

Kante is arguably the best in the world at what he does, but there's an increasingly irritating affliction whereby fans and critics have to compare anyone and everything to the Frenchman. Speak to some Chelsea fans and they'll say Kante put Matic in the shade last season. Elsewhere, he's compared favourably to Pogba when the pair fulfill completely different functions.

At United, while a combination of Matic and Michael Carrick doesn't scream pace, it certainly has poise, and you can imagine Mourinho deploying the pair together in tougher assignments. Mourinho's default setting is control, and having two solid members of his XI acting as a screen and allowing the more exuberant components like Pogba the chance to do damage further forward seems like a sensible move.

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At 6-foot-4, Matic would also be the latest recruit in Old Trafford's land of the giants. David De Gea, Eric Bailly, Pogba, Matic and Romelu Lukaku represent a fearsome spine. Yes, this is football and not the NBA, but height and power are nevertheless useful commodities, and Matic is hardly a Marouane Fellaini-style battering ram, either. The Serbia international has a good touch, an impressive range of passing and a ferocious shot. Can you imagine Fellaini even attempting this or this, never mind actually pulling it off?

A midfield masterclass at Manchester City in February 2014, where Yaya Toure was completely surpassed as Mourinho locked down a superb 1-0 win, highlights what Matic can do. Cynics will chime "that was three years ago," but Matic played 35 league matches in 2016-17 and was one of the reasons why Chelsea won the title. These are his peak years, and all being well, he should be able to provide three to four seasons of high-demand service.

United have become predictable going forward, a blight that crept in during Ferguson's final years in charge, and Fellaini's arrival exacerbated the problem. While not entirely to blame for the club's attacking malaise, it has been galling to see United hit long balls for him to chest down or flick on as they chase a goal. It's primitive, but with Matic's arrival, Fellaini is on borrowed time and could be on his way out of the club with reports of interest from Galatasaray.

Matic has been Mourinho's trusted lieutenant in the past and, if United can complete the deal, will play an important role in Manchester United's future.