Bournemouth handed Arsenal their first defeat of the season, taking advantage of William Saliba’s early red card at Vitality Stadium.
The French defender was sent off after 30 minutes for tripping Evanilson near the halfway line, following a poor pass from Leandro Trossard.
Arsenal, who had managed to salvage points in similar situations against Manchester City and Brighton, faced a tougher challenge playing over an hour with 10 men.
Their defense held firm until the 70th minute, when Ryan Christie smashed a brilliant strike into the top corner after a clever corner routine.
Substitute Justin Kluivert sealed Bournemouth’s win by calmly converting a penalty nine minutes later, following a foul by David Raya on Evanilson.
The victory ended Bournemouth’s four-game losing streak in this fixture and lifted them to 10th in the table.
For Arsenal, the defeat was a major setback, costing them the chance to go top before Liverpool's clash with Chelsea on Sunday.