Manchester United inflicted a miserable weekend on Chelsea as Jose Mourinho won his personal duel with Antonio Conte and helped shunt the champions out of the Premier League's top four.
Former Chelsea man Romelu Lukaku scored and set up the winner for Jesse Lingard in a 2-1 defeat for Conte's team, whose bid for a Champions League place was further hit by victories for Liverpool and Tottenham Hotspur.
At the other end of the table, seven clubs are separated by just four points but West Brom look down and out after a fourth straight Premier League defeat against Huddersfield.
AFP Sports looks at the major talking points from the Premier League weekend.
Chelsea on the slide
After the opening half hour on Sunday, Chelsea looked on course to move level on points with United as they deservedly led through Willian's opener.
However, they are now six points adrift of Mourinho's men as they wilted after the break.
"At the end we are talking about another defeat," said Conte, whose side have now lost three of their past four league games.
"We must be disappointed because when you have this type of situation you have to manage the game better with experience and maturity to get three points. Instead for another time we are talking about a loss."
Worse could be to come for Chelsea as they make the daunting trip to City next Sunday, while Spurs, Liverpool and United face Huddersfield, Newcastle and Crystal Palace next weekend.
Awful few days for Arsenal
If losing the League Cup final in a meek 3-0 submission to Manchester City was not bad enough, Arsenal also saw Tottenham, in fourth, open up a 10-point gap on their north London rivals.
Arsene Wenger's men now realistically need to inflict just City's second league defeat of the season when the sides meet again on Thursday to remain in contention for the top four.
"Arsenal really needs to win against City or then the distance will be too big for them like it happened for us last season," said United manager Jose Mourinho.
United salvaged Mourinho's debut season at Old Trafford by qualifying for the Champions League via the Europa League.
But even that route looks less likely for Arsenal than a few days ago after they drew AC Milan in the last-16.
103 not out for Liverpool
Liverpool's 100th goal of the season may have come from an unlikely source as Emre Can got the ball rolling in a 4-1 rout of West Ham at Anfield.
However, the familiar three then took over as Mohamed Salah, Roberto Firmino and Sadio Mane took their combined tally for the campaign to 66.
Jurgen Klopp declared the display "a joy to watch" and beyond even his own expectations.
Tellingly, Klopp also highlighted the importance a 10-day break before Saturday's clash had been to help his side reach peak performance.
The German has rotated more than any other manager in the Premier League this season and Liverpool look refreshed rather than running on fumes for the final stages of the season as they have in Klopp's previous two seasons.
West Brom cut adrift
West Brom boss Alan Pardew admitted he had "a bag-and-a-half packed" even before Saturday's 2-1 home defeat to Huddersfield, given his inability to turn the Baggies fortunes around.
Reports say Pardew will be handed one more week to save his job when West Brom travel to Watford this weekend, but time is rapidly running out not only for Pardew's prospects of remaining in charge but West Brom's chances of survival.
Seven points now separate them from safety with just 10 games remaining.