A second-half goal from Joao Pedro saw Brighton come from behind to draw after Arsenal had Declan Rice sent off in an entertaining game in north London.
It looked as though the Gunners were going to continue their perfect start to the season when Bukayo Saka played through Kai Havertz, who lobbed Bart Verbruggen in the Brighton goal for the 38th-minute opener.
However, the game completely changed after Declan Rice was dismissed for a second yellow card in the 49th minute for delaying a free-kick being taken by Joel Veltman. The Seagulls defender could also feel lucky to have got away without picking up a card himself.
Brighton piled on the pressure after that point and drew level in the 58th minute when Yankuba Minteh’s shot was parried into the path of Pedro by David Raya and the Brazilian striker slotted the ball under the keeper.
Havertz then had a good chance to win the game when through on goal, but his effort was saved by Verbruggen, before Seagulls substitute Yasin Ayari had an effort saved by Raya late in the game.
Brighton continued to push for a winner and brought on new £39.5m signing Georginio Rutter as they looked for a magic moment, but he mistimed a header as they could not find the decisive strike.
Prior to kick-off, the feeling around the club was already positive following the deadline-day deal to bring Raheem Sterling to the club on loan from Chelsea on favourable terms.
That continued when Havertz lobbed Verbruggen for a delightful strike after a touch by Saka to set him up.
But it all started to go downhill for the Gunners from there.
Boss Mikel Arteta had his head in his hands when, having already been booked for a late foul on Veltman, midfielder Rice nudged the ball away from the Dutchman and knew a second yellow card was coming.
On his 245th Premier League appearance, this was Rice’s first ever red card.
Arsenal lost any control they had in the match when they went down to 10 men, although Havertz did waste a good opportunity to claim his second goal.
Losing Rice for one match will be a blow to Arteta who will be without new signing Mikel Merino for a number of weeks with a suspected fractured shoulder that he picked up in his first training session with the club.
The Gunners will feel they have a stronger squad than last season but will now be without two key midfielders – and questions will once again be asked whether they need a lethal finisher after the crucial Havertz miss.
Brighton came into this game on the back of an excellent start to the season, winning their first two matches, and even though they went behind, they responded strongly.
They lost the experienced James Milner early in the game to injury and brought on 20-year-old Swede Ayari to help them continue their attacking approach.
Arsenal, and particularly Saka, looked like they would overwhelm the Seagulls early on, but the visitors stuck to their principles and showed their talent.
Kaoru Mitoma flashed a volley wide in the first half, while Pedro’s leveller shifted the momentum in their favour with the extra man.
Brighton have been aggressive in this transfer market and spent £195.7m as they look to take the next step and try to develop into a club that continually qualifies for Europe.
Manager Fabian Hurzeler will be delighted in how his team played, but feel this was a missed opportunity to take three points against one of the title contenders.
