Chelsea and Tottenham Hotspur were the main winners of round 28 of the 2016/17 Premier League season, with Liverpool, Arsenal, and Manchester City all dropping points on an important weekend at the top.
Arsene Wenger's tactical failure against West Bromwich Albion in the West Midlands is the headline story, but Pep Guardiola and Jose Mourinho both deserve recognition for their respective strategies on Sunday.
Here are three tactical things we learnt from the action:
1) Arsenal's defensive shambles suggests the players have stopped fighting for Wenger
Arsene Wenger's 21-year reign as Arsenal manager is surely over now.
The manner of their defeat at The Hawthorns on Saturday indicates that his players, who did not battle hard enough against Tony Pulis' side, are no longer focused on a future with Wenger at the helm.
Their zonal marking from set-pieces and tendency to switch off as West Brom countered made for painful viewing for Gooners and neutrals alike.
When confidence is low, decision-making becomes more erratic and legs become sluggish, leading to the sort of disjointed performances we have seen from Arsenal lately.
But confidence alone cannot explain what happened at the weekend; Hector Bellerin's laziness in tracking James McClean directly led to the opening goal, while the second resulted from Arsenal's three-man midfield refusing to track back.
A giant hole opened up in the middle of the pitch as the Baggies poured forward, and the simplest of passes found Nacer Chadli in acres of space on the edge of the box. His delicate chip caused a goalmouth scramble from which West Brom retook the lead. The hosts completed 10 key passes overall, their seventh highest total of the season.
But the most obvious error was Arsenal's haphazard zonal marking at corners. This strategy is particularly risky when morale is low because, without a simple tracking job, individuals are more prone to being outwitted by their opponents' movement.
Erratic decision-making and unmarked goalscorers occur most frequently in zonal marking teams. It is one of many reasons why Wenger's tactical philosophy will not be tolerated for much longer.
2) Man City's clever tactical switch shows Guardiola has a keener eye than most
After an intricately creative opening 30 minutes for Man City against Liverpool, in which David Silva combined with Raheem Sterling on the right to cause havoc in behind Nathaniel Clyne, the hosts began to look jaded and the chances dried up.
Pep Guardiola instructed his players to make clever out-to-in runs and drill low crosses into the box, but by the hour-mark this feature was no longer prominent.
Few managers would have thought to tweak things as Guardiola did. Switching Sterling with Kevin de Bruyne, he brought the Englishman's trickery into the congested central zone, which in turn sucked Liverpool's three-man midfield inwards and created new space on the right.
De Bruyne – a better crosser of the ball than Sterling – capitalised on this, setting up Sergio Aguero's equaliser before creating a golden opportunity for Aguero at the death.
Wanting to re-energise the team and reopen space on the wings, few people would have made such a counterintuitive decision.
Instead of hoping his speedy wingers would return to their first-half form, (he could have brought Nolito off the bench for the tiring Leroy Sane) Guardiola did the exact opposite, testing Liverpool's increasingly tired central midfielders and taking De Bruyne out of the firing line.
The Belgian's attempts to counter-attack centrally hadn't worked all afternoon, but he looked a different player when asked to simplify his game from the right.
3) Mourinho's new 3-4-2-1 can get the most out of a playmaker-heavy squad
It is surprising that Jose Mourinho did not move to the in-vogue 3-4-2-1 formation sooner.
Jesse Lingard's wonderful solo goal resulted from a narrow United counter-attack. He picked up the ball and drove through the centre like any good number ten, but, crucially, he was afforded the space to weave and shoot thanks to Juan Mata's run alongside him.
The two playmakers overwhelmed the middle of the pitch, with the Spaniard distracting Middlesbrough's defence and creating space for Lingard's shot.
Until the end of the season at least, Mourinho must continue with a 3-4-2-1. Neither Zlatan Ibrahimovic nor Marcus Rashford do enough outside the penalty area, and so United need a double fulcrum behind their lone striker.
Best of the Week – Romelu Lukaku
Everton's want-away striker deserves credit this weekend for focusing on the task at hand and delivering yet another superb performance at Goodison Park.
Both of his goals were brilliantly taken, but what was considerably more impressive – and what will have caught the attention of his potential suitors – was Lukaku's contribution outside the penalty area.
Aside from an excellent assist for Enner Valencia's goal, Lukaku took 32 touches of the ball outside the 18-yard box, completing 19 passes and held the ball up very effectively. The recent flurry of creative energy coming from Everton's youth products is, in part, thanks to the fear that Lukaku now strikes into opponents when he is nowhere near the goal.
Even when simply trapping the ball and spraying it out wide, the Belgian often takes as many as three defenders out of the game. There is no doubt that he is ready to move to one of Europe's biggest clubs.
Worst of the Week – Watford's directionless tactics
Playing in a flat 4-5-1 at Selhurst Park, his team struggled to cope with Crystal Palace's physicality and seemed bereft of ideas when on the attack.
They completed just five key passes and managed a measly seven shots on goal on an afternoon when Mazzarri's tactical philosophy seemed more confused than ever.
Perhaps as a consequence of their constant managerial changes, Watford do not have a coherent identity; Mazzarri's team look aimless, which will probably lead to yet another new appointment in the summer.