These are the two fears of Ian Wright, as the Gunners are preparing for the season opener on Sunday with reigning champions Manchester City.
Arsenal prepares for the first campaign without Arsene Wenger taking the lead after a summer of change since 1997.
Emery has replaced Wenger in the Emirates' Dugout with a group of signings that have been drafted to refresh the team the Spaniard had inherited.
Fans have many reasons to be optimistic as Arsenal prepares for City after a promising preseason.
Wright has revealed the two concerns that had come to mind before Pep Guardiola's men's visit to North London.
"I think Arsenal are in fourth because I think the offensive players will have all the problems of the other teams, but I'm always worried about the defensive and how the players under Unai Emery start the season and understand what he wants them to be so crucial, "said Wright BBC Sport,
"They start against a city team who know exactly what they are doing, but this could be a good time to play because some of their players are back from the World Cup.
"Arsenal will play this jostling game and could hit City unprepared?
"If they do, do they have enough defense to stop City, even if City gets hit by a couple of punches?
"That could only be wishful thinking.
"After that they play Chelsea, West Ham and Cardiff, and depending on the results that could be an incredible opening or a fall of" oh oh ".
"If they come to West Ham, if they go up against Jack Wilshere, then there's a story waiting to be written there, right?"
Wright's former Arsenal team-mate Martin Keown has himself figured out how his old team will be fair this season.
And he has suggested they win a surprise win against Runaway Champions City last Sunday.
"It's going to be a very close fight for the top four, and Arsenal and Chelsea will push Manchester United all the way and have a chance to reach the Champions League," added Keown.
"Emery has more time with his team than anyone else – they were mostly all together for the entire preseason – and they could possibly bring a surprise against City on the first day."