Troy Deeney was the match-winner for Watford as the Hornets moved a step nearer to Premier League survival with a 1-0 victory over Everton in the day's late kick-off.
In a game short on quality and goal-scoring opportunities, Watford captain Deeney took advantage of some slack marking to crash home a 79th minute drive.
Substitute Cenk Tosun had a late chance to equalise from the second phase of a corner, but the Turk saw his tame header easily saved by Orestis Karnezis in the home goal.
Here's what we learned from the game at Vicarage Road.
1. Davies bringing extra dynamism to Everton's midfield
In a season that has dipped way below expectations, a whole multitude of issues have come to the fore for Everton.
From the failure to find a goalscorer to replace Romelu Lukaku, to a porous defence that has shipped goals with regularity, the Blues have in truth rarely nudged above average in any part of the pitch. Midfield, too, has often been a weakness, with Morgan Schneiderlin off colour at the base of the midfield and a dearth of creativity also apparent for much of the campaign.
Tangible improvements, though, have been made in this part of the pitch of late thanks to Wayne Rooney's positional change and the reintegration of youngster Tom Davies into the starting lineup.
Playing in a three with a better passer in Rooney and a superior ball-winner in Gueye, the teenager's dynamism has given the Blues the final piece of their midfield puzzle. Not only does Davies break lines, but his box-to-box play also allows Allardyce's men to get up the pitch much quicker than they did in the early part of the campaign.
The England Under-21 international was again effective here, as he lead Everton's counter-attacking play while also offering a helping hand out of possession.
Poor amid the uncertainty in the opening part of the campaign, Davies' improved form means Allardyce appears to have finally found the right combination in the Toffees' midfield.
2. Deulofeu endures game to forget against former employers
It looked as though the stage was set for former Everton player Gerard Deulofeu to torment his former club.
Interviewed for Watford's matchday programme, the ex-Blue spoke of his desire to impress in "an emotional game because Everton are in my heart." Spurned by Ronald Koeman for much of his second spell at Goodison Park, it seemed odds-on that Deulofeu would have the final laugh here.
But while the prospect of the mercurial winger taking on out-of-position left-back Cuco Martina filled most Evertonian hearts with dread prior to the game, they need not have worried.
In many ways this was a typical Deulofeu performance - full of running, but with moments of real quality few and far between. Rarely did he ever get the beating of opposite number Martina.
Decision-making too - so often a flaw on Merseyside - appears to have progressed negligibly since he left Goodison Park. This, in many ways, is a player who has not really kicked on for a number of years.
Nudged off the ball by Everton substitute Cenk Tosun and promptly taken off through injury, Deulofeu's evening came to an abrupt end just after the hour mark. A fitting conclusion to a disappointing day at the office against his former employers.
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3. Niasse reminds Allardyce of limitations
Few Everton players have made as much of an impression on Sam Allardyce as Oumar Niasse since the ex-Bolton manager's arrival.
Praised for his goal-scoring instinct and indefatigable work-rate, the Senegalese has come to be seen as an integral part of Allardyce's setup. A remarkable turnaround in fortunes for a player who was left without a locker at the club's training base as recently as six months ago.
Here though, Niasse was more problem than cure.
Technically deficient in his hold-up play and clumsy in the challenge, the striker reminded Allardyce and others of his limitations. Without an out ball, or someone to link with Wayne Rooney and Gylfi Sigurdsson, Everton rarely posed any real threat to their hosts.
It was no surprise to see Niasse hooked early in the second-half with the game still evenly-poised. And that, above all else, should alert Allardyce that Everton's pecking order in attack is still up for debate.
4. Gracia positivity sees Watford to victory
This was, for long spells, a match that deserved to finish 0-0.
Clear-cut chances were few and far between, with neither goalkeeper overly exerted until the final quarter. At that point, nobody could have complained if the spoils had been shared.
As space opened up, however, the sense was that three points were there for the taking for whichever manager chanced his hand.
It was a 'stick or twist' situation. Allardyce, seemingly, was happy enough with a point - and prepared to bring on holding midfielder Morgan Schneiderlin to see the match out until Watford scored.
So it was left to new Hornets manager Gracia to grab the bull by the horns. The introductions of Kiko Femenia and Stefano Okaka, together with a switch to two up front, gave Watford more potency in the final third. Only then did Everton, comfortable until that point, start to creak.
When it came, Troy Deeney's superb winner was Gracia's just rewards. A positive change deserving of an otherwise unlikely victory.
Allardyce, meanwhile, will be left to rue his own inherent negativity once again as a point slips from his grasp.
