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With all the splashy attacking signings and excitement around Manchester United's start to the season, a couple of relatively unsung heroes have been quietly going about their business in the heart of the defence.

Few would have expected Daley Blind and Eric Bailly to form United's first-choice centre-back partnership for the first three Premier League games of Jose Mourinho's tenure, but that is exactly what they have done.

And they have done it to a high level.

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United's 1-0 win over Hull City on Saturday came with the kind of attacking intent and injury-time breakthrough that used to be synonymous with the club. The strikers will get many of the plaudits, and rightly so, but Bailly and Blind were a significant part of the victory.

Indeed, Bailly was voted man of the match by followers of the club's Twitter account. On that basis, it is probably a misnomer to describe the defenders as unsung heroes given Bailly also won that award against Leicester City in the Community Shield and Bournemouth on the opening day of the season.

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Based on that kind of support, he is a shoo-in for player of the month for August.

So just why is the partnership working so well?

The first point that has to be made is they have not yet come under any kind of sustained assault, so what we are dealing with is early-season promise rather than definitive proof this partnership is the future of United's defence. But so far, they are complementing each other beautifully, enhancing each other's strengths and mitigating each other's weaknesses.

As is the system as a whole. Squawka's Dave O'Brien pointed out after the Southampton game that Marouane Fellaini is regularly dropping deep to provide aerial cover for Blind. Against Hull, it was a slightly different story.

Whereas three of the aerial duels he won against the Saints were right in front of Blind's position in the left side of defence, against Hull he was often covering on the right, filling in when Antonio Valencia made his frequent forward runs. Instead, it was Paul Pogba going up for headers in front of Blind.

Perhaps this is a function of a slightly more defensive role for Pogba on the road, though he did get forward plenty too.

Either way, it is evidence that Mourinho's tall, powerful midfielders are offering plenty of protection to their defenders.

There are a couple of interesting tactical shifts from the Louis van Gaal era that are making a difference too. Defenders clearly have fewer responsibilities in terms of providing direct ammunition to the forward players.

Van Gaal considered his centre-backs to be a key part of the possession-oriented build-up play that proved so ineffective. Mourinho, on the other hand, clearly has Blind and Bailly under orders to let the midfielders start attacks.

Time and again against Hull, when Bailly got over the half way line, he would pick a simple pass to a nearby player and retreat back into position. The same, to a slightly lesser extent, was true of Blind. The job description has seemingly changed somewhat, and the emphasis is back on defending.

That is entirely appropriate given the balance of the team. In Bailly's case it is also pertinent given how good he is at it.

The number of defensive actions a player undertakes is of questionable statistical value given how much it is affected by the balance of play in a game, the team's structure and quality of opposition.

But for what they are worth, these are the Ivorian's stats so far. In three Premier League games, he is averaging 2.3 tackles—succeeding with 100 per cent of his attempts to tackle—three interceptions, 0.3 blocked shots, 0.3 blocked passes and 5.3 clearances per game.

He has committed just 1.3 fouls per game, and his pass-completion percentage from an average of 37 passes per game is 95.5.

Incidentally, both he and Blind have played every minute so far, hence presenting these numbers as average per game rather than average per 90 minutes.

There have been key interventions in among those numbers, particularly in terms of tackling. At Wembley Stadium, he dispossessed Leicester's Jamie Vardy in the box at a crucial moment, and he has made important challenges in all three league games. Against Hull, his 62nd minute tackle on Abel Hernandez was superbly timed and perfectly executed.

He has the speed of thought and body to react when Blind needs cover too. The Netherlands international relies more on the former when Bailly is in trouble. In the 46th minute against Hull, the Ivorian was caught slightly out of position and Blind was instantly able to recognise the danger and run into position to deny the opposition space for a shot.

It was an example of his intellect compensating for his lack of physical speed.

Blind's numbers so far this season read as follows: an average of two tackles, 2.3 interceptions, 5.3 clearances, 1.7 passes blocked, 0.3 crosses blocked and 0.3 shots blocked per game. He has yet to commit a foul and has completed 90.3 per cent of his average of 51.3 passes per game.

They are ostensibly similar numbers to Bailly's, but the nature of his tackling is so different. Bailly's style is pure 21st century centre-half, reviving the art of the slide tackle previously thought to have been lost by applying a level of Swiss-watch precision timing to his physicality.

Blind, on the other hand, has become more adept at repositioning strikers with smart deployment of his centre of gravity. He is not going to win an out-and-out battle of strength with many of the division's best strikers, so he avoids getting into them.

It is almost inevitable he will have bad games again—think Watford at Old Trafford last season and the Tottenham Hotspur and West Ham United matches on the road. But against teams playing one up front, in games in which United are on the front foot, he and Bailly look assured and able.

The next test facing the pair, assuming the remainder of the transfer window does not spring a huge surprise, will be the Manchester derby on September 10. With Manchester City boss Pep Guardiola no doubt forensically studying the partnership for weaknesses, and his side blessed with plenty of attacking talent, it should be a pretty stern test.

And in truth, some element of judgement on the success or otherwise of the Blind-Bailly pairing should be reserved for after the derby. If they can impress together in that setting, it will be time to take them seriously indeed.

For now, they deserve plenty of praise. Although it is still early in their career together, they could not have got off to a much better start.

Advanced data per WhoScored.com.