West Ham United had aspirations of moving to within just three points of third-placed Chelsea but ended up dejectedly defeated at London Stadium, as Jack Harrision’s treble ended their four-match, post-Christmas winning run.

Hat-trick hero Harrison gave the visitors an interval lead with two goals either side of an equaliser from the on-fire Jarrod Bowen and, although Pablo Fornals levelled again just after the break, the Leeds striker claimed victory and the match ball on the hour.

David Moyes' men had created their own hat-trick in midweek with a third successive Premier League win thanks to victory over Norwich City and kicking off in fourth spot – a dozen places and 15 points above the visitors – the Scot named an unchanged line-up.

But having comfortably eased themselves past Leeds in the FA Cup third round last weekend, they found the Yorkshiremen to be a totally different proposition this time around as they returned to the scene of the crime for another Sunday showdown in Stratford.

Indeed, having forced two early corners, while also seeing an early Luke Ayling range-finder fly over, Marcelo Bielsa’s boys took the lead with just 10 minutes on the clock.

Bursting into the right-hand channel, Raphinha cut back to Mateusz Klich, whose low shot was parried by Łukasz Fabiański and, although the Polish stopper had repelled his compatriot’s blistering effort, he was powerless when Adam Forshaw seized on the loose ball to set up Harrison, who curled depleted Leeds ahead from 12 yards.

Having been eliminated from the FA Cup at the first hurdle last Sunday, Bielsa had made a quartet of changes as he returned to the capital with Raphinha, Forshaw, Stuart Dallas and Pascal Struijk coming in for the suspended Diego Llorente, injured Sam Greenwood plus substitutes Lewis Bate and Leo Fuhr Hjelde, who joined 15-year-old Archie Gray on the bench.

But midway through the first half, both Bate and Hjelde made quicker-than-anticipated appearances, when Forshaw and then Junior Firpo hobbled away in quick succession.

Trailing to that Harrison opener, unimaginative West Ham had failed to trouble Illian Meslier in the Leeds goal and when Michail Antonio got within range, his 15-yard screamer was brilliantly and bravely charged down by Robin Koch, who also saw the Hammers top-scorer booked for a desperate lunge on him.

On the half-hour mark, Craig Dawson somehow nodded Declan Rice’s perfectly-flighted cross wide from all of six yards to gasps of East End exasperation but within three minutes the pocket-sized Bowen gave his towering team-mate a lesson in heading.

Aaron Cresswell swung his left-wing corner towards the edge of the six-yard box and, with all attention on the Hammers big boys, Bowen – at five-feet, eight-inches – ghosted in unchecked to nod West Ham level with his ninth goal of the season.

Unfortunately for Moyes, parity was maintained for less than five minutes and, with Leeds forcing a corner at the other end, Raphinha’s flag-kick was headed goalwards by the inrushing Ayling and unmarked, just a couple of yards from goal, Harrison bundled the visitors back in front with his second goal of the afternoon.

In reply, Rice rounded Meslier before lashing into the side-netting from the tightest of tight angles, while Bowen headed another Cresswell corner over the top before Antonio was stopped in his tracks by the consequently-cautioned Koch.

In reality, Leeds could and should have been home and hosed by the break, however the escaping Daniel James spooned his shot into the gloves of the helplessly-exposed Fabiański before then firing another angled effort inches beyond the far post.

That meant that West Ham could, at least, live to fight the second half and, sure enough, within just seven minutes of the restart, they were level again.

This time, Cresswell intercepted Ayling’s deep clearance and found Rice, who released Antonio deep into Leeds territory and, although the striker failed to succeed with an attempted flick, the ball did at least end up with Fornals.

Bursting into the visiting area, the silky Spaniard glided past both the red-faced Ayling and Struijk before calmly side-footing the Hammers level from 12 yards with his fifth goal of the campaign as the statuesque Meslier stood rooted to the spot.

Yet again, though, West Ham surrendered the equilibrium within just minutes and, on the hour, Nikola Vlašić yielded possession allowing Raphinha’s to deliver an inch-perfect defence-splitting pass to Harrison, who raced unchecked into the area, where he claimed his hat-trick with a clever 12-yard chip beyond the lonely figure of Fabiański.

The crestfallen Vlašić trudged straight down the tunnel of shame as Arthur Masuaku stepped from the dug-out and, with the Croatian international still to reach the dressing room, it could have got yet worse for Moyes' men.

Lanzini’s trip on Raphinha earned the Argentinian a yellow card and, dusting himself down, the Brazilian then whipped the consequent 25-yard free-kick onto Fabiański’s left-hand angle.

With a quarter of an hour remaining, the rampant Raphinha was wreaking more havoc, this time sprinting into the right-hand side of the area and cutting back to Klich who looked to have fired home Leeds’ fourth of the afternoon. But with the ball having brushed substitute Rodrigo on the line, the effort was disallowed for offside following a Video Assistant Referee review.

If that offside decision went in home favour, then the next definitely went against them when substitute Andriy Yarmolenko – who had been booked for tripping James shortly after replacing the unfortunate Fornals – saw his close-range header wiped out by an assistant referee’s flag.

The clock was ticking down all too quickly for the Hammers, who desperately summoned 17-year-old Sonny Perkins from the bench for the final exchanges but although Yarmolenko’s shot was smothered by Meslier and Bowen somehow chested over from underneath the crossbar, by now, it was obvious that West Ham were not going to stop three-goal Harrison from departing with all three points and that match ball.

West Ham: Fabiański, Coufal, Cresswell, Diop (Perkins 87), Dawson, Rice, Bowen, Fornals (Yarmolenko 69), Lanzini, Vlašić (Masuaku 61), Antonio. Unused subs: Areola, Fredericks, Johnson, Král, Oko-Flex, Alese.

Leeds: Meslier, Ayling, Firpo (Hjelde 23), Forshaw (Bate 22, Rodrigo 65), Struijk, Klich, Koch, Harrison, Dallas, James, Raphinha. Unused subs: Klaesson, , McKinstry, Jenkins, Moore, Kenneh, Gray.

Booked: Antonio (25), Koch (44), Lanzini (61), Yarmolenko (76), Harrison (88).

Referee: Mike Dean.