Watford came from behind twice to thump Everton 5-2 at Goodison Park and earn Claudio Ranieri his first win as Hornets boss.
Everton took their first lead with just two minutes on the clock when Anthony Gordon drove into midfield and released Demarai Gray, who made his way to the byline and picked out Tom Davies to tap home.
Andros Townsend had a speculative effort parried away by Ben Foster and Gordon's header sailed just wide from the resulting rebound as Rafael Benitez's men went in search of a second.
Watford thought they had equalised after Josh King got onto the end of a loose free-kick, but the flag was up. However, a VAR check showed that the Norway international was being played onside by Gray and the goal stood.
Everton tried to reassert their dominance but were finding it hard to break Watford down again. The closest the Toffees came to re-taking the lead before half-time was when Gordon was brought down by Juraj Kucka in the penalty area, but appeals for a spot kick were dismissed.
King was denied a second from close range on the hour mark by a brilliant low save from Jordan Pickford as the visitors made life difficult for Everton.
But substitute Richarlison put the hosts back in front just seconds after coming on with a cute diving header to meet Michael Keane's cross.
Watford had a lot still left in the tank though, as Kucka rose highest from a Juan Hernandez corner to equalise, and almost immediately from kick off, King grabbed his brace after a quick counter.
Pickford was at full stretch to deny Emmanuel Dennis soon after, but could do nothing when Everton switched off and allowed King to waltz in behind and bag his hat trick.
Dennis eventually got the goal he deserved in stoppage time as Watford ran riot and left Goodison Park as deserved winners.
Everton player ratings
1. Goalkeeper & defenders
Jordan Pickford (GK) - 7/10 - Made a couple of great saves and his kicking was great as per.
Seamus Coleman (RB) - 5/10 - Solid and assured in himself, at least.
Michael Keane (CB) - 5/10 - Looked far more comfortable on and off the ball than he has in recent weeks.
Ben Godfrey (CB) - 2/10 - Deer in the headlights. Looked scared in every moment.
Lucas Digne (LB) - 3/10 - Lost Kucka for the corner for the equaliser, and was too weak for King's second and third of the afternoon.
Allan (CM) - 2/10 - Offered so little at either end and was booked for diving.
Tom Davies (CM) - 5/10 - Scored a neat goal and was up for the fight in the first half. Not so much in the second.
Anthony Gordon (AM) - 7/10 - Was Everton's best player for the hour he was on the pitch.
Andros Townsend (RW) - 5/10 - Made a few decent take-ons without ever threatening Watford.
Salomon Rondon (CF) - 3/10 - It's just not working out.
Demarai Gray (LW) - 7/10 - Another of Everton's best players brought off too soon.
Richarlison (AM) - 7/10 - Super sub. Gave Everton the quality and energy they needed, but his efforts weren't enough.
Alex Iwobi (LW) - 3/10
Watford player ratings
5. Goalkeeper & defenders
Ben Foster (GK) - 6/10 - A decent performance from the Cycling GK.
Jeremy Ngakia (RB) - 6/10 - Much better than Kiko Femenia was against Liverpool last week.
William Troost-Ekong (CB) - 7/10 - Got under Everton's skin and was solid at the back.
Craig Cathcart (CB) - 6/10 - Wasn't rubbish, which is an upgrade on recent performances.
Adam Masina (LB) - 5/10 - Ditto.
Juraj Kucka (CM) - 6/10 - Great goal to change the tide.
Ozan Tufan (CM) - 5/10 - A cog in the system but nothing more.
Moussa Sissoko (CM) - 7/10 - Relishing playing with more responsibility and seniority,
Ismalia Sarr (RW) - 6/10 - Was always a pain in Everton's backside when he was on the pitch, but not as much as Watford's other attackers.
Josh King (CF) - 10/10 - In true Football Manager style, came back to bite the hand that used to feed him.
Juan Hernandez (LW) - 8/10 - See Sarr, but with goal involvements. Superb.
Emmanuel Dennis (RW) - 8/10 - What an impact off the bench. Fresh legs to run at Everton's jaded defence worked to a tee.
Joao Pedro (CF) - 7/10
Nicolas Nkoulou (RB) - N/A