Arsenal’s flawless start to the Premier League season came crashing to an end as Brighton & Hove Albion produced an impressive performance to secure a commanding 3–0 victory at the Amex Stadium. The reigning champions struggled from the opening whistle as Brighton applied relentless pressure and took full advantage of an unusually vulnerable Arsenal defence. The hosts established a two-goal advantage before half-time, with Pascal Groß and Charalampos Kostoulas both finding the net from distance. Arsenal’s defenders failed to close down the Brighton attackers quickly enough, giving them the space required to unleash their efforts beyond goalkeeper David Raya. Mikel Arteta’s side entered the second half needing a significant response, but Brighton continued to control proceedings. Any hopes of an Arsenal comeback were effectively ended when Chema Andrés rose highest from a corner and powered home a header to make it 3–0. Poor marking from the visitors contributed to the goal and summed up a difficult afternoon for a defence that had previously been one of Arsenal’s greatest strengths. Before the encounter, Arsenal had conceded only once in their opening four league matches, with Morgan Rogers the only player to have beaten Raya. Their defensive record had been a major factor behind their excellent opening to the campaign, but that solidity disappeared against Brighton. Arsenal were equally ineffective going forward. Their attacking players struggled to create clear opportunities, while Brighton remained organised and aggressive both in and out of possession. Kai Havertz had one of Arsenal’s best opportunities to reduce the deficit during the closing stages but was unable to convert. The visitors never generated enough momentum to seriously threaten Brighton’s comfortable advantage. The result handed Arsenal their first league defeat of the season and brought their perfect start to an abrupt halt. While one poor performance is unlikely to define Arsenal’s campaign, the manner of the defeat will give Arteta plenty to consider. Defensive lapses, ineffective attacking play and a lack of urgency proved costly against a Brighton side that thoroughly capitalised on Arsenal’s mistakes. For Brighton, it was an outstanding display and a memorable victory over the defending champions. For Arsenal, it was a sharp reminder that maintaining their title defence will demand consistency and concentration throughout the season.