Chelsea surrendered another three points in their quest for a top-four Premier League finish as Newcastle United's new signing Moussa Sissoko struck in the last minute to grab a 3-2 win that left Rafa Benitez's side reeling.
It was another late horror show for third-placed Chelsea, who had led 2-1 with goals from Frank Lampard and Juan Mata before capitulating for the second time in a week, having conceded twice in the dying minutes at Reading on Wednesday.
With fourth-placed Tottenham Hotspur in action on Sunday, Everton had the chance to move above them but drew 3-3 at home to struggling Aston Villa, who led 3-1 before Marouane Fellaini's double spared Everton's blushes.
Lukas Podolski scored in the 78th minute to hand Arsenal a 1-0 victory at home to StokeCity, a result that helped the Gunners close in on the Champions League qualification places.
Leaders Manchester United were aiming to move 10 points clear of ManchesterCity when they met Fulham in the late kickoff.
Any thoughts of the title race are long gone for Chelsea, who have now managed just one win from their last six games in all competitions -- a run that will increase the pressure on Benitez.
Worryingly for Chelsea, they are leaking goals, and that was the case again on Saturday as Sissoko turned the match on its head after Chelsea seized control.
Jonas Gutierrez gave Newcastle the lead after 41 minutes with a header but Chelsea replied after the break with Lampard's fierce shot and a curler from Mata.
Former Toulouse midfielder Sissoko, one of several French signings for Newcastle during January, tapped in an equaliser after 68 minutes after Petr Cech had parried Papiss Cisse's shot.
Sissoko then crowned a superb home debut when he crashed home a 90th-minute winner after a cut-back from Davide Santon.
Chelsea remain in third place with 46 points from 25 games, with Tottenham in fourth spot on 42 points from a game less.
Everton also have 42 with Arsenal in sixth on 41.
At the bottom of the table a missed penalty from Adel Taarabt cost relegation-threatened Queens Park Rangers victory against NorwichCity as they drew 0-0 at Loftus Road.
QPR's fourth league draw in a row meant they are now six points from safety after Reading beat Sunderland 2-1.
Southampton drew 2-2 at Wigan Athletic, meaning none of the six sides at the bottom of the table before kickoff lost.
West Ham United beat SwanseaCity 1-0 thanks to a goal from on-loan Liverpool striker Andy Carroll.
Photograph: Paul Thomas/Getty Images
