It felt like a very significant weekend in the Premier League, as dismal defeats ramped up the pressure on Manchester United boss Ole Gunnar Solskjaer and his Tottenham counterpart Mauricio Pochettino.
Pep Guardiola was also left with plenty to ponder after Manchester City's injury-hit defence was brutally exposed in a shock 2-0 loss at home to Wolves that has left the champions eight points behind leaders Liverpool.
However, the Reds have their own issues to address.
Jurgen Klopp's side may have maintained their 100 per cent start to the new season by defeating Leicester 2-1 at Anfield but, as outlined below, Liverpool are still lacking in one key area of the pitch...
1) Insecure City suffer without talisman De Bruyne
Sensing the insecurity in Man City’s central defence – and noting that Patrick Cutrone’s slowness stopped him capitalising from either of his first-half one-on-ones – Wolves boss Nuno Espirito Santo moved Adama Traore up front for the final half hour at the Etihad on Sunday.
The Spaniard's two goals – both of which came after rapid counterattacks that shone a light on Nicolas Otamendi’s recklessness – obviously vindicated his manager's tactical switch.
But more impressive was Wolves’ organised shape and targeted pressing. The wing-backs tucked inside and the visitors’ lines of defence and midfield were tightly compressed, severely limiting the space in the half-spaces (the columns that run between centre-back and full-back).
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Raheem Sterling, Riyad Mahrez and David Silva almost exclusively operate in this area, which explains why all three were anonymous for much of the game.
Ordinarily, Kevin De Bruyne’s incisive passing and peeling runs out to the right pull the opposition around to open up gaps for Sterling and Mahrez, so the hosts badly missed their talisman, with Ilkay Gundogan playing considerably deeper and more conservatively.
City need De Bruyne to shift the ball into the final third and, without him, they are surprisingly poor at breaking the lines.
2) Potter piles more misery on Pochettino
Brighton's tactics at the Amex Stadium on Saturday lunchtime caught everyone off guard, and a Tottenham side clearly shell-shocked following their midweek thrashing against Bayern Munich were particularly vulnerable to an unexpected change.
For the first time this season, Graham Potter deployed a 4-4-2 with two No.10s selected in the wide positions. Both were tasked with darting infield when Brighton were in possession.
Aaron Mooy and Pascal Gross made a flat four in midfield when Spurs had the ball, but then slotted into central attacking midfield during counterattacks, and that seemed to completely bamboozle Eric Dier.
He and Tanguy Ndombele were regularly caught flat-footed in Tottenham's atrocious 3-0 defeat, repeatedly surprised by Mooy and Gross floating in on their blind side.
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It was a clever tactic from Potter, who had clearly spotted Spurs are particularly weak in the centre of the park.
It meant Brighton built confidence early on, further darkening the visitors' mood as Mauricio Pochettino scrambled to change formations and shake his players awake – first, to 4-4-2, and then, to a 3-4-2-1.
Nothing worked, largely because Brighton outfought them all over the pitch but also because Potter moved to a mirroring 3-4-2-1 for the final 10 to shore things up.
It was a tactical masterclass from the Brighton boss.
3) El Ghazi's new role shows Villa are learning fast
Aston Villa’s attacking play had looked tired and predictable in the first few matches of the season, relying on wingers crossing aimlessly into the box as Jack Grealish tried to weave through the middle without much support.
But they are learning quickly, moving Grealish out wide last weekend to give them more guile in the final third. At Norwich on Saturday, they gave Anwar El Ghazi a new role on the right in a rousing 5-1 win.
The Dutchman constantly stood in the No.10 space when the ball was out on the left, with Grealish adding another short-passing option during Villa moves.
El Ghazi combined with Conor Hourihane, John McGinn and Grealish in a similar area of the pitch to build quickly through a static Norwich defence.
Although El Ghazi crossed from the right wing to assist Wesley’s opener, he first received the pass in the middle – an area in which he has never previously shown for the ball.
As for Norwich, their 4-2-3-1 was once again far too wide when not in possession.
Daniel Farke must coach his players to become more compressed in the transitions or they will continue to leak goals – especially when facing a No.10 as talented as Grealish.
4) Lucky Liverpool still need a creative midfielder
Liverpool's form throughout 2019 has been so good that calls for Jurgen Klopp to sign a playmaker have gone away, but another narrow victory on Saturday, this time over Leicester, reaffirmed their need for a line-breaking creative midfielder.
The Reds should find a Philippe Coutinho replacement who can shake things up, the kind of player that would offer a dramatically different tactical strategy when Plan A isn’t working.
Their current trio in the middle are too workmanlike against the Premier League’s best-organised teams.
Leicester blocked the passing lanes to Sadio Mane and Mohamed Salah by sitting off Liverpool's centre-backs and refusing to budge, just as Sheffield United did the week before. Once again, the Reds were lucky to come away with three points.
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Too much creative pressure is heaped onto the full-backs in these situations. An eight-point lead might sound good, but it should alarm Liverpool fans that their xPoints tally is 16.7; their current tally is 24.
Essentially, Klopp’s side are riding their luck at the moment.
A weaving attacking midfielder would better connect the forwards together in matches like this one, moving Liverpool beyond the first midfield line and forcing the visitors to leave their compact shape, thus creating space, both directly and indirectly.
Grealish would be a good signing, as would the Leicester goalscorer on Saturday, James Maddison.
5) Man Utd pay for Solskjaer's defensive error
There is no particular need to go over Manchester United’s in-possession tactical flaws again. We all know by now how flat and lifeless they are in all areas of the pitch; how little creativity they possess.
However, in Sunday's 1-0 loss at Newcastle, Ole Gunnar Solskjaer made a tactical error in defence, changing two of his back four at a time when the visitors were finally cranking up the pressure and looked like scoring. Instead, his change led to a winner for the home side.
Solskjaer’s hand was forced by Diogo Dalot’s injury, but he could have just slotted Marcus Rojo in at right-back rather than reshuffle the pack by moving the impressive Alex Tuanzebe out of central defence.
It took them a while to adapt to the change and both Rojo and Tuanzebe were caught out of position when Newcastle countered for their winning goal.