West Ham put their disappointing run of recent form behind them with a comprehensive 4-1 win over Watford at Vicarage Road.
Goals from Tomas Soucek, Said Benrahma, Mark Noble - from the penalty spot - and Nikola Vlasic were enough to overwhelm a Watford side who looked off the pace from the first whistle, despite taking an early lead through Emmanuel Dennis.
The Hornets made three changes to the team that last played 18 days ago, bringing Francisco Sierralta, Adam Masina and Ozan Tufan into their starting lineup, while West Ham manager David Moyes recalled Michail Antonio after his goalscoring return from the bench on Boxing Day.
Claudio Ranieri had said in the build-up to the game that Watford had only been able to train together once but the early indicators were that it wouldn't affect his side - Dennis clinically giving the Hornets the lead after just four minutes.
However, the Nigerian's superb finish into the top corner would be a rare bright moment in a half, and game, that West Ham would go on to dominate.
Benrahma rattled the crossbar with a fizzing effort five minutes after Dennis' goal, before Soucek rewarded the visitors' continued attacking endeavour with an equaliser just before the half-hour mark.
Running on to Jarrod Bowen's clever reverse through ball, the Czech fired home inside Daniel Bachmann's near post to claim just his third Premier League goal of the season.
110 seconds later, the Hammers were in front; Benrahma capitalising on an error from Kiko Feminia to fire a deflected effort home from Michail Antonio's left wing centre.
Ranieri brought Joao Pedro on at the break, but the momentum continued to flow for the visitors and they would have had a third through Bowen had Soucek not fouled Dennis in the process of winning the ball back.
But a third did come for West Ham, with VAR this time playing its part in awarding a penalty. Antonio chased down a bit of a lost cause, hooked the ball into the area and Bowen was felled by a clumsy challenge from Bachmann.
Skipper Noble, back into the side for the suspended Declan Rice, stroked home the spot kick, effectively putting the game to bed with half an hour to play. There was still time for substitute Vlasic to score a stoppage time fourth, rounding off a very good day for the Hammers.
Here's how the players rated.
Watford player ratings
1. Goalkeeper & defenders
Daniel Bachmann (GK) - 5/10 - Hauled down Bowen clumsily for the penalty, with his only other real contribution a good late stop from Antonio.
Kiko Femenia (RB) - 5/10 - Found it difficult to deal with Benrahma and Antonio's movement, with the latter able to get in behind for West Ham's second after he gave the ball away cheaply. Off injured before the break.
Craig Cathcart (CB) - 4/10 - Allowed a long ball over the top to drift over his head, thinking it would go out for a goal kick. It didn't, Antonio retrieved it and West Ham won a penalty seconds later.
Francisco Sierralta (CB) - 5/10 - Made his first start since October and marked it with a display of sh*thousery worthy of an Oscar nomination. Not many dare to dance with Antonio but he didn't hold back.
Adam Masina (LB) - 4/10 - Usually marauds up and down the left but just wasn't at the races. Outclassed by Bowen time and time again.
Moussa Sissoko (CM) - 6/10 - A typically energetic display in midfield, bursting from box to box. but lacked that bit of quality to really make a meaningful difference. Won a number of headers.
Juraj Kucka (CM) - 6/10 - Shifted to right back towards the end of the first half and was one of Watford's better performers.
Ozan Tufan (CM) - 4/10 - Bypassed in midfield and looked like a player who hadn't played a competitive game in a while.
Emmanuel Dennis (RW) - 7/10 - Continued his fine run of form with a classy opening goal.
Josh King (ST) - 6/10 - A willing runner with the ball at his feet, but you felt the Norwegian's only real support would come from Dennis and Joao Pedro - not enough to break West Ham down.
Cucho Hernandez (LW) - 5/10 - Made a couple of bursting runs on the counter but offered very little substance. No surprise to see him taken off at the break.
Imran Louza (40') - 5/10 - A couple of decent touches but spent most of his time trying to wrestle back possession.
Joao Pedro (46') - 6/10 - Has plenty of talent, that much is clear, but wasn't able to show it off given the lack of quality around him.
Ken Sema (61') - 5/10 - One of the quieter half-hour cameos you will watch this season.
West Ham player ratings
5. Goalkeeper & defenders
Lukasz Fabianski (GK) - 7/10 - Had no chance with Dennis' opener but was very alert to keep out Sissoko's shot from a blistering second half counter. Made a wonderful late double stop, too.
Vladimir Coufal (RB) - 7/10 - Still isn't performing at the level he was pre-injury - but you can never argue with Coufal's energy and commitment to the cause.
Craig Dawson (CB) - 6/10 - Made it far too easy for Dennis to get his early shot away on goal - so easy that it's making a January signing look like the club's number one priority.
Issa Diop (CB) - 6/10 - Didn't do a lot wrong against a Watford side who didn't offer a real threat - but must retain the ball better. Good in the air.
Ben Johnson (LB) - 7/10 - Another promising display from Johnson. Looks completely at ease on either flank now, which is a huge positive for the Hammers. Ran his socks off, and almost his legs.
Mark Noble (CM) - 7/10 - Covered the suspended Declan Rice in the engine room and did well. Barked out instructions, organised everything and slotted his penalty home with aplomb.
Tomas Soucek (CM) - 8/10 - A freer 4-1-4-1 system allowed Soucek the freedom to push forward, something he took full advantage of with a crisp low finish. Much better all round.
Manuel Lanzini (AM) - 7/10 - Dropped deeper to collect the ball on occasion, allowing Soucek to get into advanced areas. Solid enough.
Jarrod Bowen (RW) - 8/10 - Fast becoming West Ham's most consistent performer behind Rice. Perfectly weighted through ball to Soucek and involved in plenty, including the winning of the crucial penalty and setting up Vlasic's goal.
Michail Antonio (ST) - 7/10 - Ran the channels well and showed improvement to his end product. Surprising he didn't knock Sierralta's block off given the endless needling and nudging.
Said Benrahma (LW) - 7/10 - A really bright opening 45 minutes showed West Ham what they will miss when Benrahma heads to AFCON. Scored one, hit the bar with another and was positive throughout when on the ball.
Arthur Masuaku (81') - 6/10 -
Nikola Vlasic (85') - 7/10 - Has looked much better in recent weeks and is finally off the mark with his first Premier League goal for West Ham. A simple one as well, put on a plate by Bowen.
Alex Kral (90') - N/A