Centre-half Ashley Williams handed Everton only their second league win in 11 matches with a late header after Seamus Coleman nodded home to cancel out Alexis Sanchez’s opener – his 12th top flight strike of a prolific campaign.
Defeat, Arsenal’s first in the league since their opening day reverse against Liverpool, has paved the way for Chelsea to establish a six-point lead with victory at Sunderland on Wednesday. Arsenal, meanwhile, travel to Manchester City on Sunday.
“It was a very physical game, we faced many challenges and that disturbed our game but at the end of the day we were a bit unlucky to lose,” said Wenger, whose side’s last away league defeat was against Manchester United on 28 February.
“I don’t think with five minutes to go we deserved to lose the game but we were caught on two headers. I think especially on the first one we were guilty. Maybe we made it easy for them when they became more physical. They played a real cup game.”
Arsenal had only suffered one defeat in 18 Premier League matches against Everton and surged into a 20th minute lead when Sanchez’s low free-kick was scruffily deflected past Maarten Stekelenburg by ex-Swansea skipper Williams.
But a scrapping Everton levelled on the stroke of half time when the unmarked Coleman glanced a header past a static Petr Cech following Leighton Baines’s inswinging cross from the left flank.
Mesut Ozil blazed a glorious chance from an incisive Sanchez cut-back over the crossbar, while before the hour mark Ross Barkley fizzed an effort marginally wide of Cech’s left-hand post.
After Cech had palmed away a Phil Jagielka shot, Williams consigned Arsenal to defeat by powering an 86th minute downward header from Barkley’s corner beyond the former Chelsea stopper – his maiden goal for the Toffees.
In a frantic finale, Jagielka was given his marching orders after hauling down Lucas Perez, while fellow substitute Alex Iwobi was denied by Baines’s goal-line clearance deep into stoppage time as Everton won for the first time since 30 October.