For Arsenal’s longsuffering supporters, the emotional strain is reaching unbearable levels. They could only watch in stunned disbelief as Alex Scott’s goal 16 minutes from time condemned the Premier League leaders to a defeat Mikel Arteta must fear could prove to be extremely significant.

While Arsenal’s advantage over Manchester City remains nine points for now, another loss at the Etihad next Sunday would give City an opportunity to draw level on points if they beat Chelsea on Sunday and then win their game in hand against Crystal Palace. Having set the pace since the start of October, that is the nightmare scenario Arsenal must confront after another disappointing performance that once more belied their anxieties at this crucial stage of the season.

Bournemouth were good value for their second victory in succession here after Eli Junior Kroupi gave them an early lead. Viktor Gyökeres equalised from the spot, but after the morale-boosting Champions League win over Sporting in midweek, this was a third defeat in four matches for a side that is stumbling again when it matters most.

Kai Havertz struggled as the replacement for the injured captain Martin Ødegaard and even the return of Eberechi Eze off the bench could not inspire them. The demands of a relentless schedule have tested Arsenal’s deep squad and the absence of Bukayo Saka for a fourth match in succession will be a major concern for the showdown with City.

Kroupi was deployed up front alongside Evanilson for the visitors in a bold move from Andoni Iraola that paid dividends as they extended their unbeaten run to 12 matches. The 19-year-old, who joined from Lorient last summer, became the first teenager since Coventry’s Robbie Keane to reach double figures in his debut Premier League campaign and is some prospect.

Iraola’s contract with Bournemouth expires in the summer, with reports he is being lined up to take over at his former club Athletic Bilbao. Wherever he ends up, they will be in very safe hands.

Arteta had definitely heeded his own pre-match message for supporters to get themselves up for the early kick-off and was a bundle of nervous energy on the touchline. It did not take long for his anxiety to spread as Arsenal made a slow start and Bournemouth looked increasingly threatening on the break.

So it proved when Noni Madueke failed to track Adrien Truffert’s run in the 17th minute and Ben White was far too slow to react to the danger. Truffert’s cross looped off William Saliba to the back post, where Kroupi was waiting to tap in.

A surge of relief spread around the ground when Michael Oliver pointed to the spot after Bournemouth failed to clear a Madueke corner and Ryan Christie handled in the ensuing melee, even if the Scotland midfielder clearly felt hard done by. Havertz wanted to take the penalty at first but Gyökeres insisted and Arsenal’s top scorer made no mistake from the spot to a huge roar of encouragement when the ball hit the back of the net.

Bournemouth continued to look dangerous and Evanilson tested David Raya from the edge of the area after White was again caught out of position. Arteta was swiftly down the tunnel to deliver a few home truths.

It took nine minutes of the second half for the Arsenal manager to act. Eze, Max Dowman and Leandro Trossard were summoned from the bench in an attempt to inject some urgency, but a misplaced pass from Raya that almost donated an open goal to Evanilson showed the nerves were still affecting Arsenal.

Declan Rice’s surging run ended with the England midfielder forcing Djordje Petrovic into a fingertip save as Arsenal tried to pile on the pressure. But there was always the nagging feeling Bournemouth could score again and those worst fears came true. Scott caught Martín Zubimendi napping and was able to latch on to Christie’s pass inside the area before beating Raya with a cool finish.

Gyökeres missed a golden opportunity to earn a precious point as Arsenal’s desperation grew and it was Bournemouth’s supporters celebrating at the final whistle as Arteta was forced to contemplate the unthinkable.