Before today, Arsenal had conceded just one goal in the Premier League, making this sudden defensive collapse a significant concern. Both of the opening goals from Brighton came from outside the box, but the strikes were made easier because the Arsenal defenders failed to close down the space.
Riccardo Calafiori and Gabriel were at fault for Gross's opening goal, while Gabriel and Ezri Konsa did not react quickly enough to stop Kostoulas. Arsenal backed off in almost every scenario, struggling with poor marking and a failure to progress the ball effectively under pressure against an inspired opposition.