Arsenal's 1-0 win over Sporting in Lisbon puts them in control of their Champions League quarter-final but there is work to do on Wednesday evening at the Emirates Stadium.
Pepa is a Portuguese coach who has worked at the top level in his home country and in Brazil. Here, he assesses the key tactical aspects of the first match and looks at why Rui Borges' Sporting side could still cause an upset in the second leg.
"From a tactical perspective, the match between Sporting and Arsenal at Alvalade was, in my view, a game between two excellent teams, very competitive and intense, without many clear goal-scoring opportunities, but with very interesting tactical and technical aspects.
"Looking at Arsenal, they are a top-level team, leaders of the Premier League and with a remarkable Champions League campaign in which they have 10 wins and a draw from their 11 matches.
"I would highlight, in the moment without the ball, their ability to maintain structural compactness in a 4-4-2 shape, with no issues in adopting this behaviour in deeper areas, closing central spaces effectively.
"I would also highlight their recognition of pressing triggers, which often result in near man-oriented pressing behaviours, with players who are very strong physically, allowing them to recover the ball high up the pitch.
"They recorded 19 defensive actions in the opponent's half, while Sporting had seven, which clearly illustrates the difference.
"In possession, Arsenal struggled to create clear danger despite having slightly more possession.
"Some of their key behaviours include the more anarchic - or perhaps fluid - role of Riccardo Calafiori, who starts as a left-back but then moves into central areas and even into finishing zones.
"The quality of the three midfielders - Declan Rice, Martin Zubimendi and Martin Odegaard - and their ability to escape pressure to receive and connect play, as well as Noni Madueke's one-on-one ability, who was frequently targeted, were also important aspects.
"It is inevitable to mention Arsenal's offensive set-pieces, being the best team in Europe in attacking corners. At Alvalade, they had four corners, did not score, but hit the crossbar once.
"Regarding Sporting, considering the quality of the opponent, they delivered a very positive performance.
"I believe that the team's experiences this season in the Champions League, facing top opponents such as Juventus, Bayern Munich and Paris Saint-Germain, allow them to approach these types of matches with greater confidence and maturity.
"From a defensive standpoint, Sporting presented the dynamic structure they have used in several matches, alternating between a 4-4-2 mid-block, where when Arsenal built with a back three, Pedro Goncalves sometimes positioned himself slightly higher and joined Luis Suarez and Trincao, and a 5-4-1 in a lower block, with Geny dropping into the back five.
"This behaviour is already well assimilated by the team and, combined with strong character and a tremendous competitive spirit, allowed them to neutralise the opponent's intentions - with the exception of the goal conceded.
"Special mention should be given to the performances of Ousmane Diomande and Maxi Araujo in Sporting's defensive sector, although it seems important for Maxi to show more caution in the number of fouls committed, especially considering the areas where they occur. He committed seven fouls in the first leg.
"In possession, Sporting faced difficulties in their build-up, with some errors, particularly from Goncalo Inacio, but mainly due to the strong pressure applied by Arsenal.
"Against the opponent's defensive organisation, Sporting managed to create problems mainly through the wide areas, with Maxi on the left and Geny Catamo on the right."
"Sporting will have to remain true to themselves, imposing their strengths and being even more focused, consistent and effective than in the first match, knowing that the difficulties will be even greater.
"Sporting played that first leg in a completely favourable environment, supported by their fans, and will now play away from home and, above all, with a negative first result.
"However, we have already seen this Sporting team surpass themselves more than once, and I believe that after that first match, despite all the difficulties, belief will be very strong.
"Something that seems relevant will be the players that Sporting can recover from injury for the match. Morten Hjulmand returns after suspension, the captain and a key figure in the team's dynamics.
"Other players, such as Quenda, will also be important, particularly as options during the match. Increasingly, we see the importance of players coming off the bench and helping the team, as was the case for Arsenal in Lisbon with Gabriel Martinelli and Kai Havertz.
"I also believe that set-pieces will be important. If Arsenal are the best team in Europe in attacking corners, Sporting are the fourth best, which means this could be a decisive moment in the match."
