As if there was not enough embarrassment, Declan Rice’s final touch completed the humiliation. Arsenal were already 5-0 up at West Ham and cruising towards a resounding victory in the Premier League title race when the former Hammers captain stepped up to curl in a sublime sixth from 25 yards. As Rice’s thumping strike flew past the goalkeeper Alphonse Areola, to add to his two previous assists, the midfielder held up his hands in a gesture of apology. Yet, with thousands already having made their way to the exits and an early Tube home, the catastrophic damage had been done.

While Arsenal backed up last weekend’s statement win over Liverpool with a brilliant display of their title credentials, and their biggest away win in Premier League history, the questions will now turn to how fatal this thrashing at the London Stadium will be for David Moyes. The manager who led West Ham to their historic victory in the Europa Conference League last season was left to look on at the unfolding car crash with a hauntingly anguished expression. The mood has turned so quickly. Moyes had the Hammers within touching distance of sixth place before kick-off, but West Ham are now winless in seven and this capitulation felt ominously bleak.

Arsenal were magnificent, West Ham porous and fortunate their dismal collapse did not result in an even heavier defeat. At the third attempt, Rice returned to haunt his former club. Beaten by Moyes’s side twice this season, the Premier League’s set-piece kings responded in style to ensure there would be no hat-trick with another showing of their new-found strength: Rice’s pinpoint deliveries set up headed goals from Arsenal’s centre-back pair, first William Saliba and then Gabriel Magalhaes. Before half-time, Leandro Trossard curled in a delightful fourth, adding to Bukayo Saka’s penalty, with further goals from Saka and Rice completing the rout.

Mikel Arteta’s side were dominant from the start and relaxed into their rhythm following Saliba’s opening header at the back post. Rice’s previous two meetings with his former side had ended in ignominy, knocked out of the Carabao Cup in November before Arsenal were stunned by the visitors at the Emirates after Christmas, yet he had the last laugh here. The England international was taunted with chants of “You should have signed for a big club”, as he stood over an early corner. It was from this position that his inswinging crosses devastated West Ham’s pitiful excuse of a defence.

Saliba’s header gave Arteta’s side their 11th goal from a corner in the Premier League this season; no team has scored more and Arsenal’s proficiency at the dead ball has given the Gunners an extra dimension this campaign. For one, set-piece goals can open up tight games and deep defences, which is what West Ham were expected to be following their 2-0 shutout at the Emirates just six weeks ago. This should have been another awkward test for Arteta’s title challengers but they rose above the noise that followed their celebrations against Liverpool to show they can keep pace with Jurgen Klopp’s leaders and Pep Guardiola’s champions.

Yet there was nothing complicated about this thrashing, or the opening set-piece routine that started it. As Arsenal outnumbered West Ham at the back post, Saliba had the simple task of heading past the stranded Areola after climbing above the flailing Edson Alvarez. The second, too, came from a simple ball over the top, as Saka rounded Areola and won the penalty after a clumsy collision caused by the goalkeeper. Saka, who had been so threatening in setting the tone from the right, stepped up to double Arsenal’s lead with his 50th for the Gunners. He would later add his 51st.

Throughout it all, West Ham were abject, their defenders culpable. Vladimir Coufal had played Saka onside as the England winger raced in behind, then Ben Johnson’s calamitous decision to drop from his defensive line ensured Gabriel was onside to meet Rice’s wonderful free-kick. When it came to Trossard’s fourth, the defending from West Ham was non-existent. The Belgian, who was sharp throughout and pulled together Arsenal’s attack as he filled in for Gabriel Jesus, was shown onto his right foot by Kurt Zouma before curling in a sumptuous finish. It was far too easy.

With it, a spectacular collapse was complete. On 32 minutes, Arsenal were in control but being held at 0-0, yet 15 minutes later West Ham were four down. It would get worse, as Saka was allowed to glide onto his left foot by an ambling Nayef Aguerd to make it five after the break. The defining principles of a Moyes side, and the characteristics of last season’s Europa Conference League, had been ripped into tatters by Arsenal’s blitz. It was a tough watch for the few thousand who remained.

But the most painful blow was the final one. Already with two assists, Rice produced another gloriously curling strike to add Arsenal’s sixth, as he ran onto a cut-back that had been missed by the excellent Martin Odegaard and the equally troublesome Trossard. And immediately after completing the humiliation, Rice was withdrawn, his job in closing the gap to Liverpool back to two points complete. In the wreckage left behind, Moyes now faces a fight to keep his own position.