Arsenal slipped up in the race for the Premier League top four as they succumbed to a surprise 3-2 defeat to Crystal Palace at Emirates Stadium.
Hunting an 11th straight home league victory, Unai Emery's side looked to have shrugged off a poor opening 45 minutes when Mesut Ozil cancelled out Christian Benteke's opener early in the second half.
But Arsenal's suspect defence came back to haunt them when Shkodran Mustafi and Bernd Leno failed to deal with a hopeful punt from deep – Wilfried Zaha latching onto Christian Benteke's knockdown to restore Palace's lead.
Palace added further gloss to a fine performance soon after, James McArthur taking advantage of more slack defending to head in, with Pierre-Emerick Aubameyang's strike a mere consolation.
Despite a bright start from the Gunners in which Ozil and Matteo Guendouzi wasted decent opportunities, the visitors were ahead in the 17th minute.
Having allowed Scott Dann a free header five minutes prior, Arsenal's defence was found wanting once again when Benteke nodded in unmarked from Luka Milivojevic's free-kick.
Aaron Wan-Bissaka was then fortunate when referee Jonathan Moss deemed that he had not handled Sead Kolasinac's cross in Palace's area.
Alex Iwobi was introduced at half-time and Emery's decisiveness swiftly paid dividends as the substitute combined with Alexandre Lacazette to play in Ozil, who lifted a cute finish over Vicente Guaita from a tight angle.
Guaita had to be at his best just before the hour, diving to his right to keep out Kolasinac's stinging effort, but for all Arsenal's pressure, Palace moved back ahead when Benteke got the better of Mustafi, Zaha making no mistake after beating Leno to his strike-partner's flick-on.
McArthur made matters worse eight minutes later, heading in unchecked from a corner, and though Aubameyang cut the deficit soon after, Arsenal ultimately slipped to their first home league defeat since August.
What does it mean? Top four race wide open
And though the Gunners remain well in the race for a Champions League finish, they may have blown their best opportunity to get ahead of the pack.
Zaha in bullish form
Zaha has acknowledged that he may have to leave Palace in the off-season as he aims to further his career, but if these final games are to be his swansong for the Eagles, then he is sure to leave on good terms.
The winger was in exceptional form on Sunday and capped off his display with a typically composed goal.
Arsenal's set-piece struggles exposed
Despite Emery hauling the shaky Konstantinos Mavropanos off at half-time, Arsenal's defence never got to grips with Palace's front line and, having conceded from a set-piece for Benteke's opener, a simple long ball and another corner did the damage for the away side after the interval.
Key Opta Facts
- Crystal Palace avoided defeat in both league meetings with Arsenal in a campaign for the first time since 1979-80.
- Arsenal suffered their first home league defeat in a London derby since January 2016 (1-0 versus Chelsea) – they were unbeaten in 13 such games prior to this loss (W10 D3).
- Palace's win saw Roy Hodgson became the seventh different manager to win a Premier League away game at both Highbury and Emirates Stadium (also Alan Curbishley, Alex Ferguson, Gerard Houllier, Harry Redknapp, Jose Mourinho and Kenny Dalglish).
- Palace have scored 29 goals away from home in the Premier League this season; their most in a single campaign in the competition and joint-most overall in a top-flight season (also 29 in 1991-92).
- Palace striker Christian Benteke made his 200th Premier League appearance in this match against Arsenal. He scored 46 goals in his first 100 games in the competition, but has netted just 24 in his second 100 appearances.
- Benteke scored first his goal for Crystal Palace since April 2018 (versus Leicester City), ending a run of 19 appearances, 25 shots and 358 days without netting.
The quick turnarounds continue for Arsenal, who travel to Wolves on Wednesday. Palace are next in action against Everton on Saturday.