The title race heat went up a notch as Chelsea made their mark, Arsenal continued to put pressure on the leaders and Liverpool imploded at Bournemouth.
Here, we take a look at what was learned from the latest round of games in England's top flight.
1. The champions are in major trouble
Pulling off a repeat of last season's shock title win was always unlikely, but Leicester have disintegrated this season and are in a relegation battle. In boss Claudio Ranieri's words, "everything is wrong".
They are just two points above the bottom three after Saturday's 2-1 defeat at Sunderland - their seventh loss of the season - and a haul of 13 points is the worst record after 14 games of any defending champion in Premier League history.
The Foxes have lost six of their last seven away games in the league and, while Wednesday's Champions League trip to Porto offers brief respite, Ranieri must revive Jamie Vardy, with no goals in 16 club games, and the misfiring Riyad Mahrez.
They have failed to replace N'Golo Kante, who joined Chelsea in July and has helped the Blues to the top, and the club's summer recruitment is now coming under scrutiny. Only two buys started on Saturday, Ron-Robert Zieler and Islam Slimani, and the Foxes look like they have missed their chance to build on their historic title win.
2. Chelsea are title contenders again
Following their awful title defence last season and Antonio Conte's summer appointment, there were justifiable question marks over how Chelsea would perform this season.
But Saturday's 3-1 win at Manchester City laid down their biggest marker of the season and they are now the team to beat in the title race and sit three points clear of nearest challengers Arsenal.
Diego Costa and Eden Hazard have rediscovered their form and Conte's 3-4-3 system continues to pass every test, even when faced with the quality and brute force of City.
No European football will undoubtedly help their cause - as Leicester proved last season - and after only adding Marcos Alonso and N'Golo Kante in the summer, Conte has turned the Stamford Bridge club around after last season's disastrous campaign.
3. Liverpool still have a soft underbelly
Jurgen Klopp has turned Liverpool back into serious title contenders, but Sunday's 4-3 defeat at Bournemouth showed the fragility which has so often stopped them from challenging in the past.
The Reds disintegrated on the south coast after leading 2-0 and 3-1, to lose their 15-game unbeaten run and miss the chance to close the gap at the top to a point.
With the attacking flair of Roberto Firmino, Divock Origi, Adam Lallana and the injured Philippe Coutinho, the Reds have riches going forward, but they still lack title-winning defenders and a goalkeeper, with midfielder Lucas Leiva playing as a makeshift centre-back at Bournemouth.
Until they strengthen at the back Liverpool will continue to come up short, no matter what Klopp does at Anfield. Joe Hart appears to have no long-term future at Manchester City after his loan at Torino ends and would be the ideal buy for Klopp.
4. Manchester United can kiss goodbye to the title and Champions League qualification
Manchester United are 13 points behind leaders Chelsea and six points adrift of the top five as a title challenge continues to elude them.
Their 1-1 draw at Everton on Sunday, after Leighton Baines' late penalty, saw United fall further behind in the race for the top four, with that already looking like a five-horse race.
Jose Mourinho's arrival was supposed to turn them back into a superpower, but they have dropped seven points from goals conceded in the last 10 minutes of Premier League games this season, a league high.
Mourinho himself has won just 36 points from his last 30 league games and, despite United's huge summer spending, they are no closer to returning to the top.
5. Sunderland are finally on the up
The Black Cats have won three of their last four games to lift themselves to within a point of the safety line following their awful start to the season.
David Moyes had to wait until November for his first Premier League win as Sunderland boss, but the ex-Manchester United manager looks to be finally getting it right at the Stadium of Light.
Saturday's 2-1 win over Leicester left the Black Cats as the form team in the bottom six, and in the evergreen Jermain Defoe, who scored again, they have an eight-goal striker who can shoot them to safety, with another crucial clash at Swansea coming on Saturday.
The club have been trapped in a vicious cycle of hiring and firing during recent relegation battles and have partly survived because of the ineptitude of other teams, and Moyes will hope their mini run points to better times ahead.