Arsenal’s luck had to run out sooner or later. Mikel Arteta’s side finally surrendered their unbeaten start to the season after William Saliba was sent off – their third red card in their opening eight matches – as Bournemouth celebrated a famous victory thanks to goals from the substitutes Ryan Christie and Justin Kluivert.

It was an evening to savour for their manager, Andoni Iraola, who saw his enterprising team record their first win over a side in the top half of the table since beating Manchester United in December. For it to come against Arteta – who grew up playing for the same youth team in San Sebastián – made it particularly sweet. But with Bukayo Saka having not made the trip to the south coast, Arsenal had looked short of inspiration even before Saliba’s red card swung the balance of the game.

Arteta admitted before kick-off “there was no point pushing” Saka with games against Shakhtar Donetsk and Liverpool to come after he returned early from England duty owing to a hamstring injury. That meant Raheem Sterling was retained from the win over Southampton before the international break and Mikel Merino made his first start in midfield. There was also a timely return for Ben White in defence, while Bournemouth made three changes from their disappointing defeat to Leicester last time out.

Iraola acknowledged this week that, while their expected goals data indicated they should be fourth in the table, the onus was on his players to “become a more efficient team”. They made their intentions clear from the start here as Alex Scott and Marcus Tavernier were deployed in attacking roles supporting the centre-forward Evanilson and Riccardo Calafiori had to clear a dangerous early free-kick from Lewis Cook.

A clever touch from Sterling following another Bournemouth corner almost created Arsenal’s first opportunity but Leandro Trossard could not quite break free. David Raya was then fortunate that his wayward pass to Scott didn’t result in a goal as Antoine Semenyo blazed over from distance.

Iraola and Arteta spent the majority of the first half an hour cajoling on the edge of their technical areas as both sides cancelled each other out in a midfield battle.

But the game suddenly came alive when Trossard inadvertently played the ball over his own defence and Saliba brought down Evanilson as the Brazilian raced through on goal. A red card looked to be the likely outcome, although the referee Robert Jones initially only cautioned the France defender. With the PGMOL chief Howard Webb watching on from the stands, however, VAR thought differently and Saliba was off. He will now be missing when Liverpool visit the Emirates next Sunday.

Merino came close to finding a breakthrough after good work from Sterling before the England forward was sacrificed for Jakub Kiwior to shore things up at the back. Semenyo had already forced Raya into a good save at his near post by then and Tavernier should have opened the scoring from his cross after Raya had initially fumbled before recovering to block the shot. Meanwhile, Arsenal’s supporters made their disgruntlement known with several chants directed at Webb and other perceived injustices.

Semenyo should have done better with a golden chance that fell to him 90 seconds after the restart after a clever backheel from Milos Kerkez. But having already played the best part of 90 minutes with 10 men in the draws against Brighton and Manchester City earlier this season, once again Arsenal showed they are not easy to break down even in the absence of Saliba at the heart of their defence.

Any breakthrough seemed destined to come down Arsenal’s right side as Dango Ouattara caused White continual problems. So it was a surprise to see him make way as Iraola made three changes just after the hour mark, while Gabriel Martinelli almost had an instant impact off the bench when his cross was cleared at the last minute by Marcos Senesi. Kepa Arrizabalaga’s heart must have been in his mouth when he passed the ball straight to Merino, only for the Bournemouth goalkeeper to redeem himself by saving Martinelli’s shot.

It was from their next attack that Bournemouth finally found what they had been looking for. A clever short corner from Lewis Cook was dummied by Justin Kluivert and that allowed Christie to apply the finish with aplomb.

Semenyo could have doubled their lead after Arsenal failed to clear another corner but could not direct his shot on target. They didn’t have to wait long though as an underhit backpass from Jakub Kiwior led to Raya bringing down Evanilson inside the area and Kluivert stepped up from the spot to leave Arsenal to lick their wounds.