Liverpool’s bubble burst on a dismal afternoon at Anfield.
All the optimism generated by such a promising start to the new campaign was swept away as Brendan Rodgers’ side crashed to a damaging defeat.
Not since September 1963 when Geoff Hurst and Martin Peters did the damage had the Hammers tasted victory in L4.
Yet the Londoners deservedly ended that barren run as Liverpool produced a performance which was bafflingly feeble in all departments.
The Reds were left to rue more than simply the loss of their unbeaten record as Philippe Coutinho’s dismissal means he will miss the trip to Old Trafford on September 12.
Rodgers cried foul over referee Kevin Friend’s decision to send off the little Brazilian early in the second half.
There was certainly no malice attached to his sliding challenge on Dimitri Payet but by going to ground he was asking for trouble, especially having picked up a cheap booking for dissent before the break.
By then Liverpool already had a mountain to climb as goals from Manuel Lanzini and Mark Noble had put West Ham firmly in the ascendancy.
The Reds’ revival under Rodgers had been built on defensive solidity with three successive clean sheets enabling them to collect seven points out of a possible nine.
But this was a throwback to the dark days of last season as Liverpool’s blundering back four dished out gifts which the Hammers gleefully accepted.
Dejan Lovren will inevitably bear the brunt of the criticism after his shambolic part in the second goal.
Having taken steps towards transforming his Anfield career in recent weeks, the £20million Croatian centre-back regressed.
But Martin Skrtel hardly covered himself in glory either as he struggled throughout. Suddenly, a recall for unused substitute Mamadou Sakho doesn’t feel too far off.
Friend was atrocious, riling Anfield with a succession of baffling decisions, but he wasn’t responsible for Liverpool’s plight.
The official evened up the sides late on when he ridiculously brandished a straight red in Noble’s direction but it mattered little.
The Reds were already resigned to their fate by then and Diafra Sakho added a third in stoppage time.
With captain Jordan Henderson and Adam Lallana still missing due to injury, Rodgers named an unchanged side following Monday’s goalless draw at Arsenal, but this was a world away from that pulsating display in the capital.
Inside three minutes they had shot themselves in the foot.
Skrtel’s weak header from Payet’s cross, dropped to Aaron Cresswell at the far post. The former Tranmere left-back fired cross goal and Lanzini, who is on loan from Al Jazira Club, stole in front of Joe Gomez to divert it home.
Roberto Firmino hammered against the woodwork soon after but Liverpool rarely spluttered into life as an attacking force.
Questions will inevitably be asked about Rodgers’ tactics after he stuck with the midfield trio of Lucas Leiva, James Milner and Emre Can.
They may have thwarted Arsenal on a night when Liverpool saw little of the ball. But this was a very different assignment which required guile and creativity to break West Ham down and they couldn’t provide it.
In the first half Liverpool had 71% possession but didn’t manage a single shot on target. There was no spark, no ingenuity. It was all far too predictable.
Rodgers responded by bringing on Alberto Moreno for the ineffective Can and switching to three at the back.
Moreno’s first contribution was to make a vital sliding challenge on Cheikhou Kouyate, who had burst on to Payet’s through ball.
Hopes of a fightback were effectively dashed in the 52nd minute when Coutinho got his marching orders. As he sloped off, there was a sympathetic pat on the back of his head from his manager.
The introduction of Danny Ings for the disappointing Firmino lifted the Reds. Direct and purposeful on his debut, Ings left you wondering what might have happened had Benteke had some company earlier in the contest.
With 12 minutes to go it was 10 v 10 when Friend somehow decided that Noble deserved to walk for a challenge on Ings.
Anfield sensed that all was not lost but the response from the Reds was virtually non-existent. From Benteke’s nod down, Lovren was unable to turn it home from close range.
In stoppage time, West Ham rubbed salt into gaping wounds. Skrtel senselessly backed off and Sakho made him pay by beating Mignolet.
This was Liverpool’s heaviest home league defeat for a decade.
Having taken some promising steps forward, this was a giant leap back.