Arsenal failed to halt their dismal Premier League form as Everton claimed a 2-1 victory to keep the pressure on Mikel Arteta.
The Gunners, without injured captain Pierre-Emerick Aubameyang, have now gone seven league games without a win after Yerry Mina's header and Rob Holding's own goal lifted Everton up to second.
Nicolas Pepe's penalty had restored parity at Goodison Park, where Arteta spent six-and-a-half seasons as a player, but it was not a platform from which Arsenal could build.
Though Jordan Pickford's error led to David Luiz hitting the post, Mina's 45th-minute header ultimately proved enough for Everton to secure a third straight win from a game which saw just four attempts on target.
Michael Keane was just inches away from breaking the deadlock as Everton started in confident fashion, and an opener came when Dominic Calvert-Lewin's header from Alex Iwobi's cross diverted in off Holding.
Eddie Nketiah sliced wide from Kieran Tierney's cutback to waste Arsenal's first chance, but Tom Davies' blind challenge on Ainsley Maitland-Niles handed the Gunners a reprieve.
Pepe made no mistake, sending Pickford the wrong way with a cool finish – the Ivorian's sixth straight successful penalty.
Bernd Leno thought he had kept the scores level heading into the break with a stunning save from Calvert-Lewin, yet Everton restored their lead when Mina headed in from Gylfi Sigurdsson's subsequent corner.
Despite the setback, Arsenal came out quickly after the restart, with David Luiz hitting the upright after Pickford flapped at a cross.
Ben Godfrey's powerful run nearly resulted in Calvert-Lewin snatching a third for Everton on the counter, before Richarlison went close to teeing up Iwobi.
Arteta turned to Gabriel Martinelli with just under 20 minutes left, though the visitors' best chance did not come until the dying seconds when Pickford kept out Bukayo Saka's low drive to condemn Arsenal to an eighth league defeat of the season.
What does it mean? Differing anniversary celebrations
These sides faced each other at Goodison Park on December 21, 2019 – the day Ancelotti was appointed as Everton manager and a day after Arteta had taken charge at Arsenal – though neither were on the touchline in that game.
Ancelotti will mark a year at the helm with his team five points off leaders Liverpool while, should Brighton and Hove Albion beat Sheffield United on Sunday, Arsenal would drop to 16th.
Mina's first-half late shows rolls on
All of Mina's last four Premier League goals have now come in the 45th minute or first-half stoppage time.
The Colombia international made a decisive impact at one end, but also impressed in defence, making two tackles, while his defensive partner Keane made a game-high five clearances.
More own goal woe for the Gunners
Arsenal are finding it hard enough to score at the other end, without putting through their own net. The Gunners have scored three own goals in the Premier League this season, only scoring more in 2002-03 (four) and 2011-12 (five).
In a twist of irony, Holding is the first Arsenal player to score an own goal against Everton in the Premier League since Arteta himself did so in April 2014, in a 3-0 defeat at Goodison.
Key Opta Facts
- Arsenal's 14 points from 14 games this season is their worst record at this stage of a season since the 1974-75 campaign (12 points, converted to three per win).
- Everton have won two of their last three home league games against Arsenal, as many as in their previous 11 against them at Goodison Park.
- After a run of just one win in seven Premier League games, Everton have won each of their last three, guaranteeing them a spot in the top four at Christmas for the first time since 2004-05.
- Arsenal have not scored from open play in any of their last five Premier League away games, with their two goals on the road since Alexandre Lacazette's strike against Liverpool coming from the penalty spot.
- Pepe has more goal involvements in all competitions than any other Arsenal player this season, with the Ivorian the Gunners joint-top goalscorer (five) and assister (three) this term.
Both teams are in EFL Cup quarter-final action, with Arsenal facing another of Arteta's old teams in the form of Manchester City on Tuesday, a day before Everton host Manchester United.