Conte's tactics change and Harry Kane's injury in top six's key moments
While Tottenham and Chelsea are in a scrap to the finish for the Premier League title, the other members of the "Big Six" have fallen by the wayside.
For each club this season, there have been moments to alter momentum, key matches or events to shift focus in the campaign.
So as Manchester United, Arsenal, Liverpool and Manchester City face a fight for the top four while Spurs and Chelsea battle for the league, ESPN FC examines the key moments that have shaped each club's season.
Chelsea: Arsenal embarrassment brings tactical change
At the Emirates on Sept. 24, Chelsea looked leggy and ageing as goals from Alexis Sanchez, Theo Walcott and Mesut Ozil put them to the sword 40 minutes in. After 10 minutes of the second half, Chelsea boss Antonio Conte had seen enough, and switched a previous 4-2-3-1 formation to 3-4-3.
That move brought the end of the Chelsea careers of both John Terry and Branislav Ivanovic, and made key players of wing-backs Victor Moses and Marcos Alonso. They would not concede a goal for six matches, as part of a 13-match winning streak that ended at Tottenham in a 2-0 loss on Jan. 4..
They have led the league since beating Everton 5-0 on Nov. 5, though recent defeats to Crystal Palace (2-1) and Manchester United (2-0) suggest another rethink might now be required.
Tottenham: Living without Kane
Harry Kane is back from an ankle injury for Spurs, though they barely missed him this time around. They scored 17 goals in the 400 Premier League minutes he was missing, before his April 8 return in a 4-0 defeat of Watford.
Lessons were clearly learned from the striker's previous absence, when a September ankle injury ruled him out for almost seven weeks. Spurs won the next two league matches, including beating Manchester City 2-0, to deliver Pep Guardiola a first defeat in English football. But the three draws that followed, 1-1 against West Brom and Leicester either side of a 0-0 draw with Bournemouth, may eventually prove fatal.
Liverpool: Klopp's dry January
Liverpool entered 2017 in second place, but a 2-2 draw at lowly Sunderland on Jan. 2 removed them from a height they are yet to return to. It preluded a desperate, winless run for Jurgen Klopp's team, in which only League Two's Plymouth Argyle would be beaten until a 2-0 Feb. 11 defeat of Tottenham. That was a lone victory in 11 matches.
There were reasons for such a slide, with Sadio Mane at the African Nations Cup and Philippe Coutinho making a tentative return from injury, but questions were raised about Klopp's ability to negotiate the heavy demands of an English fixture list when he has always made good use of German football's winter break. Liverpool won just three from 10 during the same period in 2016.
Manchester City: Celtic stop the procession
There have been multiple twists and turns in Manchester City's season. The brief flowering and then loss of Gabriel Jesus to injury comes to mind, but City's current status, hanging on to a Champions League place for next season, would have seemed inexplicable when Guardiola was presiding over 10 successive wins from the start of his reign.
"We will lose games and we will make mistakes, but this is a process," he predicted on Sept. 17.
City did not lose at Celtic in the Champions League 11 days later, instead drawing 3-3, but Brendan Rodgers' team showed others the way in how they pressed their opponents. City lost their next match 2-0 to Tottenham, undone by a similar approach, and would not win for another month. It was at this point that Guardiola's obsessive tinkering with personnel and tactics became a hindrance rather than strength.
Manchester United: Derby day brings limbo
The seeds of Jose Mourinho's long stay outside the top four were planted as early as his team's fourth match of the season. United vs. City on Sept. 10 was the first blockbuster of the campaign, with two 100 percent records on the line. City's devastating first-half display won the day in a 2-1 victory, and United dropped to third, only to lose 3-1 at Watford the following week to drop to seventh.
On Sept. 24, a 4-1 defeat of Leicester lifted United to sixth, where they have ended 18 rounds of the season since, despite Mourinho's team going on unbeaten run that now stretches to 22 matches. They are in fifth, but the Europa League remains the club's best hope of reaching the Champions League.
Arsenal: Stung by the Hornets
The failure of Arsenal's Premier League season, with fourth place looking beyond reach, has many causes. When did Arsene Wenger's problems begin? The loss of influential midfielder Santi Cazorla to a season-long Achilles' problem in October during a 6-0 defeat of Ludogorets would seem a decent place to start, though Arsenal lost only three of their next 21 matches.
They were in second place when Watford travelled to the Emirates on Jan. 31, but have never recovered from a 2-1 defeat. Since then, Alexis Sanchez's future has become cloudy, as has Mesut Ozil's. Arsenal are conceding cheap goals, and 19 successive years in the Champions League look to be at a sorry end.
John Brewin is a staff writer for ESPN FC. Follow him on Twitter @JohnBrewinESPN.