Leno’s late error consigns Arsenal to a 1-0 defeat against Everton.
This was a tight match throughout, and it was unsurprising that it was settled by a single goal.
In a remarkable week during which the actual football has been overshadowed and felt irrelevant following attempts of 12 greedy clubs, including Arsenal, to form a European Super League this was no different.
Even with both still playing for a place in more accepted European competition, Arsenal and Everton were going to have to produce something special to take the spotlight away from the scenes outside the Emirates.
Arsenal fans came out in force, descending on the ground in their thousands to send an emphatic message to despised owner Stan Kroenke, the focus of their protest, originally planned to voice their ESL objections, shifting once that shambolic venture collapsed.
Their fury had not altered though and the result that followed would have done nothing to diffuse the angry mood.
Fan power had managed to help get that ridiculous idea binned so why not unite and assemble to remind Kroenke he is unwelcome and unwanted too?
Calvert-Lewin and Richarlison went close for the visitors in the first half, as Arsenal dominated possession without threatening.
However, the hosts improved after the break and could have taken the lead when Chambers flashed a volley narrowly over.
The game was decided on a mistake though, as Leno fumbled Richarlison’s cross over the line to give Everton the lead in the 76th minute, and the visitors held on to secure a first league double over Arsenal since the 1985/86 season.
Bernd Leno tried his best with a comical late own goal to gift Everton a victory, one that would have been that little bit sweeter in light of their fury at the breakaway plans of their rebel Premier League rivals.
The result means that Everton climb past Arsenal into eighth, who drop into ninth.