Michael Cox assesses how the Red Devils' chalk and cheese widemen suffered in south Wales on Sunday...
While Manchester United's lack of firepower remains a problem, Louis van Gaal's side started their 2015/16 campaign with three clean sheets in three Premier League games, an impressive defensive record. In fact, taking into account their two Champions League qualifiers, they only conceded one goal in their first five games of the season – and that was an unfortunate deflected own goal.
But their trip to Swansea on Sunday was perhaps their first real challenge of the season. And while Daley Blind's centre-back credentials were given a real test by Bafetimbi Gomis, it was also a huge examination of their young full-backs, up against a team who generally prosper by attacking at speed down the flanks. Peculiarly, Luke Shaw and Matteo Darmian actually struggled more when they didn't have any direct opponents.
Shaw and Darmian are in different situations – one accustomed to Premier League football, the other a newcomer – and they're also very different types of full-back. Darmian is more of a classic one, while Shaw offers a more attacking, modern interpretation of the role.
Italy generally produces safety-first full-backs; often players like Darmian, who are capable of playing on both sides of the pitch. Darmian is naturally a right-back, but an odd one. He doesn't have a particularly good right foot – interestingly, he uses his left hand for writing, perhaps suggesting he's somehow ambidextrous, and he's spent some of his career playing on the left.
Darmian feels like a player who has learned the game rather than been blessed by a staggering ability to play it, and his positional sense and willingness to tackle are more striking than his ability on the ball. He's a good player going forward, but perhaps in the Pablo Zabaleta mould, storming forward with power and with well-timed runs, rather than with outrageous technical quality.
Shaw, on the other hand, offers tremendous acceleration when going forward, and naturally overlaps his winger to stretch the play before swinging crosses into the box. His balance is particularly impressive when dribbling, and he can launch crosses on the run without breaking stride – he's more an Aleksandar Kolarov type.
United's visit to Swansea was odd, however. Darmian's defensive performance was questionable, while Shaw was caught out because he was attacking with too much gusto.
Darmian will have been delighted when he realised Swansea were without Jefferson Montero, the flying Ecuadorian winger who has caused Branislav Ivanovic and Daryl Janmaat serious problems so far this season. Wayne Routledge was instead his direct opponent, and aside from one moment when he conceded a free-kick for a clumsy foul early in the second half, he had few problems.
Both of United's full-backs were culpable for the concessions, though. Swansea changed system from a 4-2-3-1 to a narrow 4-3-1-2, which meant Shaw and Darmian had licence to push forward into attack more – but perhaps they did so too much.
For Swansea's opener, both of Manchester United's full-backs were caught high up the pitch, as the away side launched a counter-attack. But a misplaced pass meant Swansea counter-countered, and their move effectively exploited the gaps on either side of the United centre-backs. Gylfi Sigurdsson burst into the space where Shaw might have been, then crossed deep to the far post for Andre Ayew, taking advantage of the fact Darmian was nowhere to be seen.
Something similar happened for the second goal. This time it was Ayew breaking into the space behind Shaw, and he curled a wonderful ball into the path of Gomis. With United's centre-backs shifting across to cover for Shaw, Darmian had to sweep in behind and couldn't quite catch Swansea's French hitman.
Their overall performances, though, were what we've come to expect. Shaw played far more crosses than Darmian, creating two chances, including the assist for Juan Mata's opener.
And Shaw's defensive work came higher up the pitch. He remains a more impetuous defender, particularly illustrated by the fact he committed three fouls in advanced positions. Darmian defends in a calmer, more reserved way.
While both could do with improving their positioning and ironing out defensive mistakes, United seem to have the right balance from their full-backs – one overlapper, one defender. Given time to develop, they should be United's full-back pairing for many years to come.