New manager Sean Dyche enjoyed a dream start as a much-improved Everton side stunned Premier League leaders Arsenal at a raucous Goodison Park.
Dyche was appointed last Monday following the departure of Frank Lampard, who was sacked with the team in the relegation zone.
And the hosts picked up their first victory in 11 games in all competitions courtesy of a link-up between two men who played for Dyche at Burnley.
Centre-half James Tarkowski rose at the far post to power home a header from Dwight McNeil's corner to spark the sort of joyous scenes that have been witnessed rarely at Goodison this term.
Everton had enjoyed much the better chances in the opening period too, but striker Dominic Calvert-Lewin could not convert from the excellent Amadou Onana's low cross and also flicked a header wide.
Arsenal were outfought for large periods and failed to find any rhythm, although January signing Leandro Trossard forced Jordan Pickford into a sharp save late on.
The Gunners were unable to find the leveller and will see their lead at the top cut to two points if champions Manchester City beat Tottenham on Sunday.
Everton show much-needed fight and grit
Thousands marched down Goodison Road before kick-off, protesting against Everton's board and its running of the club.
But what a transformation there has been on the pitch in just five days under the experienced Dyche.
The former Burnley boss has already set about changing the mindset of a team who have been abject this season.
Writing in his matchday programme notes, Dyche asked for "hard work" and a demonstration of the "pride" of wearing the Everton shirt - and he got both.
Setting up in a 4-5-1 formation, Everton snapped into tackles and gave high-flying Arsenal no room to breathe - with Vitalii Mykolenko's late challenge on captain Martin Odegaard in the second minute setting the tone.
The home side's pressing and ferocious tackling was epitomised by Belgium midfielder Onana, who made more tackles - four - than any other player on the pitch, with each challenge greeted by a roar from the home fans.
Calvert-Lewin could possibly have done better with his chances but could not find the target, while Abdoulaye Doucoure - restored to the team after a falling out with Lampard had led to him being omitted - sent a free header wide.
It did not cost them though, as Tarkowski nodded in at the back post on the hour mark before wheeling off to celebrate a goal that ended a run of four consecutive home defeats with a statement win.
It was just their fourth league victory in 21 games this season, taking them out of the relegation zone by a point, but they could return to the bottom three depending on other results this weekend.
Huge setback for Arsenal
Arsenal have swept aside almost everyone put in front of them this season, but this is a major setback for Mikel Arteta and his team.
The free-flowing football that has lifted them to the top of the table was absent and they did not look like scoring after falling behind, succumbing to their second league loss of the campaign.
They had defeated Manchester United and north London rivals Tottenham with impressive performances in their previous two league games, but may well have Pep Guardiola's City breathing down their neck by Sunday evening.
Arsenal's performances this season have fuelled talk of a first league title since 2004, but if they fail to beat Brentford in their next game, they could be second by the time they host City on 15 February.
Eddie Nketiah wasted a presentable opening in the opening period, blazing wide, while Bukayo Saka did the same in the second half.
Deadline-day signing Jorginho came off the bench to make his debut, but the Italy international was unable to create any chances for his team-mates.
Player of the match
OnanaAmadou Onana
Line-ups
Everton
Formation 4-5-1
1Pickford
23Coleman30Coady2Tarkowski19Mykolenko
7McNeil16Doucouré27Gueye8Onana17Iwobi
9Calvert-Lewin
1PickfordBooked at 86mins23Coleman30Coady2Tarkowski19MykolenkoBooked at 63mins7McNeil16Doucouré27Gueye8OnanaBooked at 69mins17Iwobi9Calvert-LewinSubstituted forMaupayat 62'minutesBooked at 90minsSubstitutes
4Holgate11Gray13Mina15Begovic20Maupay22Godfrey26Davies29Vinagre50SimmsArsenal
Formation 4-3-3
1Ramsdale
4White12Saliba6Gabriel35Zinchenko
8Ødegaard5Partey34Xhaka
7Saka14Nketiah11Martinelli
1Ramsdale4WhiteSubstituted forTomiyasuat 85'minutes12Saliba6Gabriel35ZinchenkoBooked at 90mins8ØdegaardSubstituted forFábio Vieiraat 77'minutes5ParteySubstituted forJorginhoat 59'minutes34Xhaka7Saka14Nketiah11MartinelliSubstituted forTrossardat 59'minutesSubstitutes
3Tierney15Kiwior16Holding18Tomiyasu19Trossard20Jorginho21Fábio Vieira30Turner85Cozier-DuberryReferee:David CooteAttendance:39,314Live Text
Match ends, Everton 1, Arsenal 0.
Second Half ends, Everton 1, Arsenal 0.
Foul by Takehiro Tomiyasu (Arsenal).
Neal Maupay (Everton) wins a free kick in the defensive half.
Oleksandr Zinchenko (Arsenal) is shown the yellow card.
Neal Maupay (Everton) is shown the yellow card.
Oleksandr Zinchenko (Arsenal) wins a free kick in the defensive half.
Foul by Neal Maupay (Everton).
Foul by Leandro Trossard (Arsenal).
Idrissa Gueye (Everton) wins a free kick in the defensive half.
Attempt missed. Oleksandr Zinchenko (Arsenal) left footed shot from outside the box is high and wide to the left. Assisted by Bukayo Saka following a corner.
Corner, Arsenal. Conceded by Vitaliy Mykolenko.
Attempt missed. Oleksandr Zinchenko (Arsenal) left footed shot from outside the box is high and wide to the left. Assisted by William Saliba.
Corner, Arsenal. Conceded by Idrissa Gueye.
Jordan Pickford (Everton) is shown the yellow card.
Substitution, Arsenal. Takehiro Tomiyasu replaces Ben White.
Foul by Eddie Nketiah (Arsenal).
James Tarkowski (Everton) wins a free kick in the defensive half.
Attempt saved. Neal Maupay (Everton) left footed shot from outside the box is saved in the bottom left corner.
Hand ball by James Tarkowski (Everton).
Our coverage of your Premier League club is bigger and better than ever before - here's everything you need to know to make sure you never miss a moment