08/04/2017 14:00 v West Ham United
The Swans' relegation fears worsened after a 1-0 defeat to West Ham at the London Stadium.
Cheikhou Kouyate's first-half strike - just before the break - proved the difference in a game where the visitors failed to really trouble Hammers keeper Darren Randolph.
Paul Clement's side remain two points adrift of fourth-bottom Hull City with six games to go, while the Hammers ended a five-match losing streak.
The Swans failed to settle in the opening exchanges, with West Ham on top.
Manuel Lanzini showed the hosts' intentions when he flashed a 30-yard free-kick just over the crossbar.
Minutes later, Lukasz Fabianski produced a fantastic save to keep Robert Snodgrass' header out, with the Polish keeper's outstretched hand preventing it from fully crossing the line.
Fabianski was again called upon on the half-hour mark as he reacted well to push out Andre Ayew's goalbound effort.
The Swans attacked in patches and only managed to create some half-chances.
One of those came via a corner, which Sigurdsson delivered and Federico Fernandez rose to head towards Wayne Routledge, but his attempted backheel effort was snuffed out by the Hammers defence.
Jordan Ayew then raced past James Collins down the right flank, but his cross just failed to find the onrushing Gylfi Sigurdsson.
The Icelandic international then tested Darren Randolph with a 25-yard free-kick, but the keeper comfortably gathered low down.
Then came a hammer blow as the Swans conceded with a minute left of the half.
West Ham pushed on, Lanzini's neat touch put Cheikhou Koutate within sight of goal, and he hammered a fierce effort just inside the post with Fabianski helpless.
Clement made a double change at the break as he opted for a more attacking approach.
On came Luciano Narsingh and Fernando Llorente for Tom Carroll and Routledge.
It failed to get the immediate reaction he would have wanted, with Andre Ayew crossing for Sam Byram, but he fired into the side netting.
At the other end, sub Narsingh drove his effort from Leroy Fer's chest down into the legs of James Collins.
The Swans were forced into their final change as the injured Jack Cork was replaced by Jefferson Montero.
Neither team could firmly get a grip on the game, but Kouyate's goal was the all-important factor.
Llorente glanced a Sigurdsson corner wide without really threatening Randolph while Lanzini's free-kick flew high and wide at the opposite end.
Fabianski, once again, kept the Swans in touching distance as he denied Andre Ayew from close range.
But despite huffing and puffing, the Swans couldn't find the equaliser they were looking for.
WEST HAM: Darren Randolph, Cheikhou Kouyate, Manuel Lanzini, Robert Snodgrass (Sofiane Feghouli, 70), Mark Noble (capt), James Collins, Andre Ayew (Edimilson Fernandes, 86), Sam Byram, Jose Fonte, Arthur Masuaku, Michail Antonio (Jonathan Calleri, 40).
SUBS: Adrian, Havard Nordtveit, Andy Carroll, Diafro Sakho.
SWANS: Lukasz Fabianski, Kyle Naughton, Federico Fernandez, Alfie Mawson, Martin Olsson, Jack Cork (capt, Jefferson Montero, 65, Tom Carroll (Fernando Llorente, ht), Leroy Fer, Wayne Routledge (Luciano Narsingh, ht), Gylfi Sigurdsson, Jordan Ayew.
SUBS: Kristoffer Nordfeldt, Jordi Amat, Stephen Kingsley, Ki Sung-Yueng.