Arsenal would surely have taken a draw beforehand against a Chelsea team that have emerged as surprise title rivals in recent weeks – and especially when they realised they had to play without William Saliba, who injured himself in training on Saturday.

It was a different story when everything changed in the 38th minute, Chelsea reduced to 10 men after Moisés Caicedo’s X-rated challenge on Mikel Merino. It was one of those that made you wince upon each replay, the stand-in Arsenal striker fortunate to emerge unscathed.

It was Chelsea’s sixth red card of the season in all competitions – not including the one for the manager, Enzo Maresca, in the win over Liverpool in October. Now Arsenal had to be thinking about all three points; a result to give them a seven-point advantage at the top of the table.

Except it did not work out like that. Chelsea had been in fire-breathing mood at the outset. Perhaps it was part of the reason why Caicedo overstepped so grievously. And they rocked Arsenal when Trevoh Chalobah looped home a header from a Reece James corner at the start of the second half.

Arsenal had to react and they did. It was Merino who scored the equaliser, a tribute to his own tenacity as much as anything else. And it was Merino towards the end who did almost nick the win, his low shot well saved by Robert Sánchez. The Chelsea goalkeeper jumped up to block bravely on the rebound from the Arsenal substitute, Viktor Gyökeres.