The bargain hunting, Boxing Day shoppers in Westfield had a better afternoon in Stratford than the Hammers, who slumped to this forlorn festive defeat at London Stadium.

Despite twice pulling themselves level, there was little Christmas cheer for West Ham United who were left to digest the cold turkey of a fourth consecutive loss in all competitions.

Mohammed Elyounoussi sent the Saints marching towards victory with his early opener and, although half-time substitute Michail Antonio levelled soon after his arrival, James Ward-Prowse then restored the visitors’ advantage from the penalty-spot on the hour.

Still, Saïd Benrahma quickly equalised with his seventh goal of the campaign before Jan Bednarek secured all three points for the visitors with 20 minutes remaining.

Following their narrow Carabao Cup quarter-final exit at Tottenham Hotspur on Wednesday night, the Hammers made four switches as they returned to Premier League action.

Benrahma, Łukasz Fabiański, Vladimír Coufal and Pablo Fornals each came in for substitutes Alphonse Areola, Ben Johnson, Manuel Lanzini, and Harrison Ashby, who were joined on the bench by top-scorer Antonio, who was ruled out of that midweek cup-tie with COVID-19.

With the pandemic wiping out last weekend’s fixture against Brentford, the Saints had kicked off in 15th-spot – ten places and 11 points below the Hammers - having benefited from a pre-Christmas break of ten days.

And those fresh legs quickly came to the fore with the visitors taking the lead inside eight minutes after they worked the ball forward from ‘keeper Fraser Forster’s clearance deep into West Ham territory.

Collecting from Ward-Prowse, Elyounoussi then found Kyle Walker-Peters who squared his return back to the Norwegian international and he claimed his fifth goal of the season with a crisp. low 18-yarder that flew beyond Fabiański’s groping glove before scorching inside the base of the Polish ‘keeper's left-hand upright.

Ralph Hasenhüttl had also made a quartet of changes to the team that had drawn at Crystal Palace last time out, with Elyounoussi, Bednarek, Forster and Theo Walcott all returning in place of Will Smallbone, Nathan Tella and Lyanco plus substitute Willy Caballero.

And apart from seeing couple of awkward corners plus a curling Jarrod Bowen free-kick bend wide midway through the opening period, the Saints boss had barely seen his team under threat and, indeed, with a more a ruthless shot the unmarked Elyounoussi would have doubled his tally on 35 minutes but his low 12-yarder lacked pace and Fabiański gratefully gathered.

The frustration of everyone in Claret & Blue was apparent for all to see and Declan Rice was booked for fouling Armando Broja – the skipper’s fifth yellow card of the Premier League campaign that results in him being suspended for Tuesday’s trip to Watford.

Just before the break, the Hammers produced their best moment of the opening 45 minutes, when Nikola Vlašić burst clear but Forster managed to parry his low 15-yarder and as Bowen looked to snaffle-up the loose ball, Walker-Peters came to his ‘keeper’s rescue, sliding the danger behind to keep the Saints’ advantage intact at the interval.

With the Croatian’s late effort having posed the only meaningful first-half danger to Forster, Moyes made a double-switch at the break, hooking Vlašić and Fornals in favour of Antonio and Lanzini.

It was a reshuffle that paid instant dividends for within just four minutes, Bowen forced a corner that then saw him float the resultant flag-kick towards the far post, where Craig Dawson nodded on and the newly-arrived Antonio – four yards out - headed home.

Video Assistant Referee Craig Pawson ruled Antonio marginally onside to the relief of the holiday crowd and, with the cheers still subsiding, Rice came within inches of then putting the Hammers ahead but his angled 20-yarder sizzled through the Stratford mist and just wide of the Forster’s right-hand upright.

On the hour, though, VAR was not so kind to West Ham, when the retreating Dawson ended up in a terrible tangle as Broja burst towards Fabiański’s penalty area and, with Chelsea’s on-loan Albanian international having finally tumbled in the box, referee Friend consulted his pitch-side screen.

The official duly pointed to the spot amidst a chorus of East End moans and with Dawson subsequently seeing yellow, Ward-Prowse then clinically drilled his low penalty beyond the outstretched right-glove of Fabiański, who having guessed correctly still could not stop the England midfielder from netting his fourth goal of the campaign.

Back to the drawing board, Moyes boys went looking for an equaliser and, sure enough, it duly arrived within just three minutes, when Bowen raced into the right-hand channel before patiently sending his byline cutback towards the in-rushing Benrahma, who got between Mohammed Salisu and Bednarek to lash the Hammers level from eight yards.

But just when the Algerian’s seventh goal of the season looked to have given West Ham both momentum and hope of now kicking on towards victory, Southampton took just six minutes to restore their lead.

Having been booked moments earlier for scything Coufal, Broja then found himself on the end of a forceful Bowen blockbuster that earned the Hammers No.20 a yellow card of his own.

There was now yet more woe for Bowen, when Ward-Prowse whipped in the consequent 30-yard free-kick from the left flank and, with the ball arrowing into the dangerzone, Bednarek climbed highest, getting between both Dawson and Tomáš Souček to power a downward header inside the base of the right-hand upright to, ultimately, give Southampton victory.

HAMMERS: Fabiański, Coufal, Masuaku, Dawson, Diop, Souček, Rice, Fornals (Lanzini h/t), Vlašić (Antonio h/t), Benrahma (Yarmolenko 80), Bowen. Unused subs: Areola, Noble, Fredericks, Johnson, Král, Ashby.

SAINTS: Forster, Livramento, Walker-Peters, Salisu, Bednarek, Romeu (Diallo 90+3), Elyounoussi, Ward-Prowse, Walcott (S. Armstrong 88), Redmond, Broja (Adams 80). Unused subs: Caballero, Long, A. Armstrong, Peraud, Simeu, Valery.

Booked: Rice (34), Dawson (60), Broja (66), Bowen (68), Bednarek (85) Walker-Peters (90+6).

Referee: Kevin Friend