Leighton Baines’ 91st-minute penalty won Everton the most dramatic of Premier League matches against Watford – with former Blues midfielder Tom Cleverley missing a golden chance to equalise for his team deep into stoppage time, when he struck wide from the spot.
The Toffees trailed 2-0 and appeared doomed to defeat with only 26 minutes left to play.
That was to reckon without David Unsworth wielding his influence from the touchline, the Everton boss making three separate substitutions, with each new man, in turn, becoming a leading protagonist in a home goal.
Ademola Lookman laid the foundations for Oumar Niasse to score and pull Everton back into the game following strikes from Watford pair Richarlison and Christian Kabasele.
Substitute Dominic Calvert-Lewin completed a breathtaking 10-minute period when he leapt to meet a Baines corner and equalise from close range on 74 minutes.
And Baines lashed home from 12 yards after Aaron Lennon had been upended by visiting defender Jose Holebas.
If Everton’s first mission was simply to unsettle Watford, then they accomplished it with some gusto.
The Toffees’ early play was characterised by their hounding and harrying, Marco Silva’s men unable to catch their breath, with Idrissa Gana Gueye, Tom Davies and Niasse to the fore as Everton hunted in packs high up the pitch.
Unsworth demanded that effort and application as a minimum, though. The first piece of guile from the hosts came with Davies’ delicious slide-rule pass intended for Niasse, after Gueye had snapped into a challenge on halfway.
Niasse was denied by the smothering Heurelho Gomes. The manner in which the striker hungrily chased the scraps and forced Christian Kabasele to concede a free-kick – fizzed in from the right by Gylfi Sigurdsson and headed clear by Miguel Britos, requiring all of his 6ft 2in frame and a mighty leap to apply a crucial touch – typified the harum-scarum opening to this contest.
Davies was prepared to take the initiative with his running beyond lone striker Niasse, too. One such dart was balked by the covering Britos, with Davies straining to latch on to Michael Keane’s searching ball over the top.
The game was 22 minutes old when Everton could, perhaps should, have cracked Watford’s resistance.
Niasse’s determined closing won a throw-in on the right, with the Senegalese then applying his grey matter to get on with things, in an attempt to exploit the confusion momentarily sweeping through the away team’s ranks.
Davies was the recipient of Niasse’s throw, with the ball funnelled through Rooney and Niasse, again, before Rooney’s right-wing cross ran behind Davies and into the feet of the advancing Baines.
The left-back, however, seemed uncertain as to whether power or precision would be his best bet – and ended up having something of an each-way punt, a low shot which forced Gomes to save down to his right but, in truth, never looked like defeating the Hornets’ keeper.
Between times, Watford had steadily found their attacking feet. Unsworth, prowling the touchline, his coat long-since discarded, watched Jordan Pickford punch clear from a Holebas delivery. He would, though, have enjoyed seeing Sigurdsson legitimately send winger Richarlison crumpling to the turf in the immediate aftermath.
Cleverley was the player responsible for Watford’s hitherto most encouraging moment of the half. He traded passes with Andre Gray at a short corner, before bending over a cross which passed an inch beyond Pickford’s left-hand post.
Davies, deployed in behind Niasse – with Sigurdsson to his right and Wayne Rooney operating on the left – sent an opportunistic long-range effort over the top on 27 minutes.
From there, a couple of menacing Sigurdsson dead-ball deliveries aside, it was Watford who suddenly grabbed the match by the scruff of the neck.
Gray made a hash of his attempted connection on a low cross from the byline by right-back Kiko Femenia.
It was when Gray turned provider, though, that Watford appeared destined to strike a concussive blow on the home team.
The striker rolled Phil Jagielka on halfway and weighted a pass to Richarlison, racing in off the right flank, leaving Baines in his slipstream and taking a sumptuous first touch, which eliminated the onrushing Pickford from the frame.
The Brazilian’s second touch, though, could not match what preceded it for its accuracy and cunning, Richarlison’s left boot directing the ball into the side netting.
Everton now, were on the ropes, but still evading a hammer blow. Holebas’s vicious effort slammed into Davies, with the immense Abdoulaye Doucoure swooping onto the loose ball and firing in a shot that needed carefully fielding by Pickford.
The second-half was fewer than 60 seconds old when Watford’s increasing threat was converted into something tangible.
Andre Carrillo escaped down the right and slid the ball infield for Gray. He strode forward, lifted his head and spied Richarlison making a dart to the far post.
A stab with Gray’s right boot later and the ball was at his team-mate’s feet. Richarlison, once more, slipped by Pickford with his first touch.
The attacker managed what he had been unable to achieve before the interval, though, and finished the job, prodding the ball high into the net from six yards.
Gomes’s reaction stop, the ‘keeper plunging to his right, prevented Sigurdsson from equalising on 53 minutes, after Niasse had charged down the right and cut back for the Icelander.
Rooney’s return cross, lifted high into the six-yard box, was finger-tipped clear by Gomes – whose afternoon was promptly ended by the falling Kabasele inadvertently planting his foot into the Brazilian’s head.
Gomes, his head bandaged, unsteadily took his leave, to be replaced by Greece international ‘keeper Orestis Karnezis. Unsworth had already made his first change, sending on Lookman for Beni Baningime, whose maiden Premier League start had lasted 55 minutes.
Karnezis was still finding his bearings as Silva’s side broke away to double their advantage.
There were no takers for Gray’s fantastic delivery after the striker flew down the left to cross. Femenia kept play alive, though, with Baines eventually forced to concede a corner.
Holebas slung it in. The towering Kabasele headed home.
If watching his team score was Karnezis’s first act, his second was to pluck the ball from his net.
Lookman drifted infield, all urgency and intent, and lofted a ball forward, which caught Holebas on the hop and found Niasse creeping in on the Greek’s wrong side.
The Everton forward nudged the ball past Karnezis, hurtling from his goal and selling himself, and, despite Kabsele’s desperate attempts to recover the situation, forced the ball over the line.
Unsworth, one substitution having paid off handsomely, made another, Calvert-Lewin taking the place of Rooney.
The forward had been on the pitch six minutes when he equalised. The 20-year-old was instrumental in winning the corner which he ultimately converted, Calvert-Lewin completing a slick give and go with Sigurdsson before sweeping in a cross that ultimately alighted with Jonjoe Kenny.
His strike deflected behind off Holebas, with Kenny then whipping up the Howard Kendall Gwladys Street End. He got the response he was after – but it was as nothing to the reaction when Calvert-Lewin climbed at the far post to head home Baines’ corner.
It was the former Sheffield United man’s first Premier League goal this term.
Substitute Adrian Mariappa was a fraction off target with a header from another Holebas corner on 89 minutes.
And then the game’s – heavens, perhaps the season’s – defining moment.
Holebas tumbled under pressure from Aaron Lennon – on for Sigurdsson – and took Lennon with him.
Referee Graham Scott blew his whistle, paused for effect, then pointed to the spot.
There was an interminable delay while Holebas received treatment. If the wait bothered Baines he concealed it superbly, blasting his penalty to Karnezis’s right.
The goalkeeper got a hand to the ball, but without applying sufficient force to prevent it from ending up in the back of his net.
Still, Watford would not go away. Pickford could only palm Doucoure’s cross into the path of Richarlison and, as the goalkeeper hared out in a bid to atone for his error, he only succeeding in dragging his opponent to the turf.
The stage seemed set for Cleverley to land the most sickening of sucker punches on his old club.
Instead, he scuffed his right-footed effort past Pickford’s right-hand post.
Goodison Park erupted, a noise only surpassed when Scott – after 12 additional minutes - called time on the most intoxicating, compelling, thrilling and joyous game of football you could hope to witness.