A sure way to anger Jose Mourinho is to let your full-back fly forward unmarked. Given his cautious tendencies, the Portuguese has a track record of bemoaning lax wingers, from his criticism of Joe Cole to disagreements with Cristiano Ronaldo, the sale of Juan Mata and his condemning of Eden Hazard. This Sunday, when Manchester United face Chelsea, the issue may well become relevant again.

Nobody needs to tell Mourinho the cost of slack marking. His Real Madrid side conceded a last-minute goal in a Champions League semi-final leg at Bayern Munich in 2012 when Philipp Lahm was allowed to race down the line and cross for Mario Gomez, and the Spaniards were eventually eliminated. Two years later, his Chelsea team fell at the same stage partly thanks to Hazard letting Juanfran create the equaliser – and thus a crucial away goal – for Atletico Madrid at Stamford Bridge.

Hazard switches off against Atletico

Then as now, Mourinho couldn't bring himself to forgive such errors. “Eden is the kind of player that is not so mentally ready to look back to his left-back and to leave his life for him,” he said. “If you see the first goal of Atletico you completely understand where the mistake was and why we conceded that goal. The perfect team at the top level cannot make these kinds of mistakes.”

The blue wall

Conte has finally managed to tighten up his backline: he's instructed his wing-backs to track the wingers, while the wide forwards have followed the full-backs, making it 5-4-1 without the ball

That sets the scene nicely for Mourinho’s return to west London, given what Antonio Conte will throw at him. United demonstrated their solidity in Monday's drab goalless draw at Anfield, in which the wingers tracked back so diligently that Mourinho effectively used a back six at times, but they are unlikely to be accustomed to the 3-4-3 Conte has introduced. Only once have United faced a back three under Mourinho, and that ended with a 3-1 defeat by Watford.

Chelsea may well offer a sterner test than that, having recovered from a wobbly season opening that featured one clean sheet in six league games. It was after the 3-0 loss at Arsenal that Conte vowed to find a new solution to his leaky defence. At Hull a week later, he lined up in a 3-4-3, ditched Branislav Ivanovic and masterminded a 2-0 win. The clean sheet was repeated last weekend in a 3-0 victory at home to Leicester.

Those games suggest that Conte has finally managed to tighten up his backline: he's instructed his wing-backs to track the wingers, while the wide forwards have followed the full-backs, making it 5-4-1 without the ball. This may leave United with three versus two in central midfield on Sunday, but one of the Chelsea centre-backs can step up to close down the extra man. Conte may also take comfort in the fact that his right-sided centre-back Cesar Azpilicueta will offer mobile cover on the side where Marcus Rashford or Anthony Martial will play.

Wingers in disguise

Conte can push Marcos Alonso (left) and Victor Moses (right) far upfield due to the security provided by the back three

What may be of concern to United is the efficiency of the Chelsea wing-backs. Conte can push Marcos Alonso (left) and Victor Moses (right) far upfield due to the security provided by the back three, and did so to great effect against Hull and Leicester. Moses, in particular, has thrived. The issue is not only that both are more dangerous than most full-backs, but that they tend to be marked by wingers unaccustomed to tracking natural wingers, particularly so far into their own half.

At Hull, the duo were practically playing as wingers. The most dangerous one was Alonso, who set up four shots from open play and unleashed five attempts.

Yet just as telling was the influence of Moses. The Nigerian livewire set up two chances and embarked on constant raids down the flank, pulling off four dribbles.

Part of the problem for Hull was that the winger made to track Moses, Adama Diomande, is a natural striker; he scored 17 goals in 21 games in the Norwegian top division last year. While he can generally cope with regular full-backs, Moses proved more difficult to contain. This is relevant for United, because Mourinho is likely to play Rashford here, having started Martial in the 4-1 win against Fenerbahçe on Thursday.

All in the timing

There are also other dynamics at play. Particularly against Leicester, Chelsea moved wingers Hazard and Pedro infield close to Diego Costa, where they received passes to feet. This prompted the opposition full-backs to close them down in narrow positions, which in turn left spaces down the flanks that Moses and Alonso exploited. One such move involving Moses led to the corner from which Costa scored the opener, with left-winger Marc Albrighton nowhere to be seen. Towards the end, Moses got on the scoresheet himself.

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The challenge for United is about pace as well as timing. Conte rehearses these combinations so thoroughly that the wing-backs know exactly when to start their runs; when the pass down the line is played, they're already on their bikes. This makes defensive alertness particularly crucial. So much trouble did these combinations cause Leicester that Claudio Ranieri changed his beloved 4-4-2 midway through the first half in order to mirror Conte’s system.

Mourinho is unlikely to opt for such measures, and so his best bet is surely to pick diligent wingers, with Ashley Young a possible starter given his previous experience at full-back. Should Rashford play on the left, his battle with Moses could be key. Mourinho will know that halting the wide play will enable him to keep a narrow and compact shape that can deny space for Costa and Hazard. It is easier said than done, but at least the matches against Hull and Leicester have given him plenty of warnings about what may be in store.

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