The anticipation levels will rise at the Emirates on Sunday when Arsenal win their first corner of the FA Cup third-round tie, unless you're part of the Manchester United defence or assistant coach Carlos Fernandes, who will step out of the dugout and take up station on the edge of the technical area, making sure all is going to plan.

The issue for Fernandes has been that very little has gone to plan when it comes to defending set-pieces. United now practice defensive set-pieces as part of their warm-up - a trait that is catching on throughout the Premier League - but it has made little difference when the pressure of the opposition having an actual set-piece arrives.

Those problems were laid bare most clearly when United conceded twice from corners at the Emirates in early December. That night, Ruben Amorim's side kept Arsenal quiet in open play but were lucky to only be breached twice by the Gunners' devilish deliveries.

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A similar route to goal is likely this weekend. Arsenal fired a blank against Newcastle in midweek, which exposed their attacking problems once again. Without Bukayo Saka, they are finding it harder still to create opportunities in open play, and when they do, they lack a reliable goalscorer.

So they will see using their set-piece strength against United's set-piece weakness as the most likely route to winning the game. Amorim and his team should see it as an opportunity to build on the impressive performance at Anfield by winning the game and taking advantage of an Arsenal side that is not currently firing on all cylinders.

To do that, they will need to defend those balls into the box better than they did in the 2-0 league defeat at the Emirates last month. Most of the responsibility for that comes down to 29-year-old Fernandes, who has taken over set-piece duties from Andreas Georgson since Amorim and his staff arrived in November.

Speaking after United had conceded another set-piece goal against Bournemouth last month, Amorim defended Fernandes and tried to take the responsibility on his shoulders.

“The responsibility of everything is me, is not Carlos, it’s on me,” Amorim said. “We are a team, we are a team in good moments and bad moments.

“We have a way of doing things, we are working on that and we are going to improve on that also but we didn’t lose because of set pieces."

That is Amorim's way of trying to keep the pressure off his young assistant, but you can be sure that when Arsenal win their first corner on Sunday, the cameras will pan to Fernandes, up on his feet, with his club coat on, guiding his players over their roles and responsibilities.

It is a litmus test for whether United have improved in this area and for Fernandes himself. He will know that if they concede from a corner again at the Emirates, then questions will be asked.

It would also strike a negative tone in a week when on-pitch matters are finally pointing in the right direction. United's performance against Liverpool was their best under Amorim and came after a longer spell on the training ground. This week, Amorim, Fernandes, and the rest of the staff have had even longer to drill the players.

There has been a whole week between games, and that should have allowed for more sessions to improve the tactical understanding of the system and sharpen up on details, such as the set-piece defending. After the draw with Liverpool last weekend, Diogo Dalot spoke positively about the value of those extra sessions.

"It's training, it's proper training, it's time on the pitch, know what everybody wants to do, almost like trusting ourselves that everybody will be in the right position to play in every aspect of the game in every inch of the pitch," he said.

"When you have time to know what to do, I think it becomes more natural. And [against Liverpool] you saw the structure much more compact, probably a bit more playing almost like we knew that this player would be in that position."

This weekend offers another chance to highlight the value of training ground time, not just in open play but also at set-pieces.