Arsenal moved top of the Premier League with a statement 1-0 win at Liverpool as Manchester United plunged further into crisis with a 2-0 defeat at Chelsea.
Brighton could prove to be Arsenal's biggest challenge to retaining their title after the Seagulls inflicted a second consecutive defeat on Manchester City.
AFP Sport looks at three talking points from the weekend's action:
There are few feats Mikel Arteta has not achieved since taking charge of Arsenal seven years ago but a Premier League win at Anfield had eluded him until Sunday.
Arteta got the response he desired to an embarrassing League Cup exit to fourth-tier Fleetwood on Tuesday as Kai Havertz gave the Gunners an early lead.
Thereafter, though, Arsenal needed to rely on their renowned defensive resilience.
Liverpool were made to pay for not taking their chances in a dominant spell before half-time, but the Reds were completely snuffed out in the second period once Arteta restored order at the break.
Arsenal's three-point lead at the top is even more comfortable in the context that City are likely to face a huge points deduction unless they overturn a guilty verdict on over 100 charges of breaking Premier League rules.
The last time United were in the relegation zone after August was 40 years ago when Ron Atkinson’s dismissal paved the way for the arrival of Alex Ferguson and a golden era of success.
That may prove the only crumb of comfort for United fans now bunkering down for the potential of a relegation battle over a long winter.
Defeats for Nottingham Forest and Crystal Palace ensured the Red Devils remain just outside the bottom three on goal difference.
But United's downward spiral shows no sign of abating.
Michael Carrick was given a stay of execution for Saturday's trip to Stamford Bridge but was left with his head in his hands after a second-half implosion from the visitors.
United had enjoyed the better chances of a goalless first half.
Any sense of positivity was quickly erased when Morgan Rogers was allowed to rampage unchallenged through the heart of the United defence to open the scoring.
A moment of madness from Lisandro Martinez then did his under-fire manager no favours.
The Argentine was booked for two fouls, committed 83 seconds apart, to leave United down to 10 men and concede a penalty, which Cole Palmer converted.
A nine-game winless run is United's longest without victory for 38 years.
The realistic prospect of a club that should post revenues this season in excess of £700 million being relegated remains remote.
However, the fast start of all three promoted clubs, who all sit above Carrick's men in the table, means it cannot be easily dismissed.
Brighton are also dreaming of upsetting the odds but for all the right reasons.
The Seagulls have never won a major trophy but have proven they can handle the Premier League's best.
Fabian Hurzeler's men thrashed Arsenal 3-0 in September and beat City away for the first time in the club's history on Saturday.
The Premier League's top scorers have also now kept six clean sheets in nine games.
"There’s an old phrase - defence wins you battles and wins you championships," said Hurzeler.
"I said before the game it's about belief, it's about having the confidence to come here and win this game."
Brighton sit third but belief is growing they could do the impossible and emulate Leicester's shock title triumph a decade ago.
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