Huddersfield slipped closer to Premier League relegation as the bottom club blew a two-goal lead in their 4-3 defeat at West Ham, while Burnley are in deep trouble after losing 2-1 against 10-man Leicester on Saturday.
Jan Siewert's side looked to have kept alive their faint hopes of beating the drop as they raced into a 3-1 lead in east London.
But a second-half collapse culminated in Javier Hernandez's last-gasp winner for West Ham, leaving Huddersfield 16 points from safety with only seven games remaining.
Mark Noble put West Ham ahead with a 15th-minute penalty after 18-year-old Aaron Rowe, making his first professional start, brought down Manuel Lanzini.
Huddersfield were level just two minutes later when Juninho Bacuna headed in from Aaron Mooy's corner for the Terriers' first away league goal since Boxing Day.
Karlan Grant gave Huddersfield the lead with a close-range finish in the 30th minute and the January signing from Charlton scored again in the 65th minute with a fantastic 20-yard strike.
But Angelo Ogbonna reduced the deficit with 15 minutes left and Hernandez completed West Ham's gritty fightback with an 84th-minute header from Samir Nasri's cross.
Former Manchester United striker Hernandez wasn't finished yet and he struck again in the final seconds with a header from Felipe Anderson's cross.
At Turf Moor, Burnley's survival bid was dented as they were rocked by Leicester.
Leicester defender Harry Maguire was sent off in the fourth minute for a trip on Johann Berg Gudmundsson as the Burnley midfielder ran clear on goal.
It was the fastest Premier League red card in four years, but Leicester weren't fazed as James Maddison opened the scoring with a superb 33rd-minute free-kick.
Burnley's teenage forward Dwight McNeil equalised with a fine finish in the 38th minute.
But Leicester snatched the points in the 90th minute when defender Wes Morgan struck after Youri Tielemans' cross deflected into his path.
Burnley are one place and two points above the relegation zone, with third-bottom Cardiff holding a game in hand.
In the day's other game, Matt Ritchie's last-gasp equaliser rescued Newcastle in their 2-2 draw at Bournemouth.
Salomon Rondon blasted Newcastle into the lead with his 10th goal of the season, this one a powerful free-kick on the stroke of half-time.
However, Josh King equalised with 48th-minute penalty awarded for Federico Fernandez's foul on Nathan Ake.
King's second goal arrived in the 81st minute after good work from Dominic Solanke, but Ritchie had the last word with a fierce half-volley.
On Sunday, Liverpool can replace Manchester City on top of the table if they win at Fulham, while Chelsea look to improve their top four prospects at Everton.