Arsenal’s perfect start to the Premier League season ended emphatically as Brighton produced a dominant 3-0 win at the Amex Stadium, exposing defensive frailties and a lack of composure under pressure in Mikel Arteta’s side.

Pascal Gross opened the scoring in the 31st minute with a powerful shot that took a slight deflection off Gabriel before beating David Raya. Charalampos Kostoulas doubled the lead on the stroke of half-time, and Chema Andrés made it 3-0 in the 57th minute, heading in from close range after a corner. The result ended Arsenal’s seven-match winning run across all competitions and their nine-match unbeaten league streak dating back to April.

Arteta was blunt in his assessment, saying his players did not “respect” the basic principles needed to play out against Brighton’s aggressive man-to-man press. He pointed to poor distribution from Raya and individual errors from Riccardo Calafiori, Gabriel and Ezri Konsa that put Arsenal under immediate pressure and prevented them from establishing control. “When we did regain the ball, the amount of technical errors we made … we didn’t respect any principle of play that you have to get out of those man-to-man situations,” Arteta said.

Alan Shearer, speaking on BBC Radio 5 Live, said Brighton “absolutely battered” Arsenal and could have scored “six or seven” given the quality and volume of their chances. He praised Brighton’s strength, fitness and fearlessness, arguing the scoreline flattered the visitors.

Late drama arrived when Declan Rice was booked in the seventh minute of stoppage time for kicking out at Malick Yalcouye in an off-the-ball incident. VAR reviewed the challenge but upheld the on-field yellow card, with no further action taken. For Arsenal, the defeat is a stark reminder of the margins in a title defence; for Brighton, it is a statement win that underlines their top-four credentials.