West Ham United's outside hopes of securing a top-four finish in the Premier League have all but ended following a heavy 4-1 home defeat to Swansea City this afternoon.

The Swans opened the scoring completely against the run of play through Wayne Routledge 25 minutes in, while Andre Ayew added a second prior to the break to put his side on their way to a first win at Upton Park since 1956.

Ki Sung-yueng's goal early in the second half essentially ended the contest, and the Hammers' hopes of ousting Manchester sides City and United for a Champions League berth, with Diafra Sakho's close-range finish proving to be a mere consolation.

There was still time at the death for Bafetimbi Gomis to add a fourth for Francesco Guidolin's side, putting the icing on the cake following what had been an explosive match in the English capital.

An action-packed first half should have kicked off with the home side taking the lead, but Lukasz Fabianski produced a strong hand to turn away Dimitri Payet's long-range drive, before collecting Winston Reid's headed attempt from the resultant corner.

Payet was involved again soon after when sending a free kick from 25 yards out onto the roof of the Swansea net, but the Hammers' dominance in the opening quarter of the match counted for little when the visitors found the breakthrough.

From their first attacking move of the afternoon, Ki picked out Kyle Naughton down the right, who simply side-footed a first-time pass into the path of Routledge to knock in his second goal of the season.

It was made to look easy by the Swans, but it really should have been all square once more three minutes later when Fabianski flapped at a corner which allowed Angelo Ogbonna to shoot at a gaping goal.

The defender fluffed his lines, sending the ball well over the bar, and it proved costly as Stephen Kingsley - making the most of a rare start - got the better of Michail Antonio and sent in a killer ball for Ayew to do the rest from a few yards out.

Twice West Ham had been caught out and twice Swansea had punished them, but stand-in stopper Darren Randolph did at least manage to keep out Ki's weak header at the back post to prevent a third.

A frantic end to the half began with Modou Barrow blasting wide when played through down the right-hand channel, before Payet curled his latest attempt into the hands of Fabianski from just inside the box.

A mixture of Andy Carroll and Manuel Lanzini failed to find the net from under the bar in the final act of the half, ensuring that the Welsh outfit somehow took a comfortable two-goal lead into the interval.

Despite arguably creating the better chances, West Ham were incredibly three down seven minutes into the second half after Ki this time profited from a decent delivery from the hosts' right flank, sending his volley past Randolph from the centre of the box.

Carroll's hopes of making an instant response were thwarted by a strong Fabianski stop, while the Englishman also sent another shot wide after Antonio had himself been denied by Swansea's Poland international.

The Swans, who had not scored three goals in a single Premier League game prior to last weekend's win over Liverpool, were finding gaps to run into as the game wore on, and looked just as likely to score the game's fourth as their opponents.

However, a first away win in five for Swansea did not look as straightforward all of a sudden when the Londoners deservedly pulled one back 22 minutes from time through Sakho.

The substitute flicked the ball into the roof of the net after Antonio became the latest to be frustrated by Fabianski, although a little touch off Kingsley may see it go down as an own goal.

Momentum was very much back on the Hammers' side, but they struggled to really push on in search of a second that would have ensured a grandstand finish in the final traditional Saturday kickoff to be staged at Upton Park.

A much-changed Swans side, showing six alterations from last time out, almost piled on the misery a few minutes from time when Antonio flicked the ball onto his own crossbar.

Naughton was only denied a goal of his own from a powerful strike by a smart Randolph save in the final minute of play, but Swansea had already done more than enough to end their barren away run and even netted a fourth through a Gomis breakaway goal at the death.