Arsène Wenger strode purposefully towards the fourth official, Craig Pawson. The Arsenal manager was a long way from his technical area and there was steam coming out of his ears. His team were in the lead, thanks to Jack Wilshere’s goal, which, after all the midfielder’s injury misery, was a beautiful moment for him.

But the referee, Anthony Taylor, had pointed to the penalty spot and all of Wenger’s conspiratorial pre-match fears had seemingly been realised. Wenger had railed against poor officiating against his team this season and Taylor always stood to be a central character. Wenger had clashed with him last January to earn a four-match touchline ban.

There was no injustice here. Hectór Bellerín’s lunge at Eden Hazard inside the area was not just ill-advised, it was reckless. He caught Hazard’s foot, the Chelsea forward went down and, if the fall seemed exaggerated in real time, Taylor’s decision was vindicated with every replay.

Hazard beat Petr Cech from the penalty spot and things came to look even more bleak for Wenger and Arsenal when the Chelsea substitute, Davide Zappacosta, rinsed the inexperienced wing-back, Ainsley Maitland-Niles, to cross for Marcos Alonso, who touched home in front of the flat-footed Shkodran Mustafi.

Enter Bellerín, again. In stoppage time, at the other end. After Alonso had only half-cleared with a header, Bellerín crashed a half-volley goalwards and it was still rising when it ripped into the net. On this occasion, his timing was glorious.

Arsenal did their best to throw it away. Not for the first time their patched-up back-line evaporated into the night sky and there was Álvaro Morata, running on to a simple long ball, with only Cech to beat. He could not do so – the goalkeeper stood up to make his most important save of the game – and Zappacosta rattled the rebound against the crossbar.

Wenger looked shot to pieces at full-time, overtaken by the emotion, and he saw conspiracy at every turn. He wanted to talk about the spectacle and how entertaining it had been, which was certainly true. Why could we not discuss the football alone? In the next breath he was throwing around some pretty serious accusations about how he knew his team would be punished by the referee. Again.

This was the latest harum-scarum Emirates Stadium ride – after the 3-1 loss to Manchester United and the 3-3 draw against Liverpool. The common denominator has been Arsenal’s defensive looseness and their desire to engage their opponents in a toe-to-toe slugfest. Wenger’s team have played with so little control and structure that it has been difficult to argue their wounds have not been self-inflicted.

It would have been worse had it not been for Morata, who endured a torrid evening. The Chelsea striker’s first one-on-one chance came on 14 minutes after Calum Chambers had inexplicably ducked underneath Victor Moses’s hopeful punt forward and Mustafi had melted away.

Suddenly Morata was in and he opened up his body for a side-footed finish. He botched it horribly. Morata would also shoot high after brushing past Chambers in the 68th minute. The angle was tighter than his other openings but it remained a glaring miss.

Wenger’s hand had been forced by the injuries to Laurent Koscielny, Nacho Monreal and Sead Kolasinac, and his callow replacement back-line was jittery throughout. But Wenger is not the sort of guy to dwell on defending. His focus, as usual, was on what his team could create.

They enjoyed a purple patch leading up to the midway point of the first half and they would have led were it not for the reflexes of Thibaut Courtois. He tipped Alexis Sánchez’s shot on to the inside of his right-hand post and watched the ball run across his line, kiss the other post and spin to safety. The Chelsea goalkeeper then saved from Alexandre Lacazette after the striker had spun sharply away from Gary Cahill.

The thrills and spills were plentiful – together with the belly laughs. Maitland-Niles provided one of the latter when he clipped his own heel inside the Chelsea area on 16 minutes and went down. He was lucky to escape a yellow card. Wilshere, who was booked for a foul on Cesc Fàbregas, flirted with a second caution when he went to ground too easily from a challenge by Andreas Christensen. He might not have been on the field to score his goal – a thumping, first-time, left-footed drive.

Hazard shimmered with menace while Fàbregas twice teed up Tiémoué Bakayoko before the interval with sumptuous passes. From the first Bakayoko saw Cech tip over while he did not read the second. Fàbregas shot high when well placed on 45 minutes but he was otherwise excellent. When he was substituted some of the Arsenal supporters rose to applaud him.

Fàbregas played in Hazard early in the second half only for Cech to save while Courtois denied Lacazette at the other end. Mesut Özil had gone close before Wilshere bludgeoned Arsenal into the lead, after Rob Holding’s low pass had flicked off Morata. Lacazette promptly worked Courtois but the game would turn sharply on the Chelsea penalty.