The Premier League currently finds itself with the most impressive array of managers in its 27-season history, and the eclectic cast includes three managers who have contributed significantly to the evolution of modern football.
The first is Manchester City's Pep Guardiola. His hugely successful Barcelona side repopularised possession football across the continent before he became an increasingly flexible manager during his period in the Bundesliga with Bayern Munich. The second is Liverpool's Jurgen Klopp, whose use of pressing and gegenpressing at Dortmund created a high-tempo, all-action side that won two Bundesliga titles and reached the European Cup final.
The third is Chelsea's Maurizio Sarri. Unlike the other two, he can't point to a glittering list of honours, but anyone who consistently watched his Napoli side was blown away by the intricacy of his side's possession play.
Sarri hasn't entirely imposed his Napoli model on Chelsea, but his contributions to the Premier League could be particularly significant over time. In fact, they could eventually push the Blues to the title.
Guardiola and Klopp borrowed from one another. Klopp was influenced by the speed at which Guardiola's Barca won possession. Guardiola was impressed by the pace of Klopp's Dortmund on the counter-attack and increasingly worked on new structures to guard against such speed on the break. Between them, they have developed new ideas on possession play and pressing, the two major concepts in modern football.
Sarri's sides are slightly different. He's much closer in style to Guardiola, but his approach is a response to sides that have adopted Klopp's philosophy and made pressing the fundamental part of their philosophy. Guardiola's early Barcelona side played out from the back under little pressure because pressing wasn't such an ingrained concept. When it became increasingly popular and Barcelona and Bayern were pressed more, they were forced to adapt and bravely play through it.
Meanwhile, Sarri actively encourages his sides to be pressed. His Napoli side was notable for the long periods it spent holding on to the ball in defence, teasing the opposition with quick passes between the defenders, baiting the strikers to push forward from their deep block and engage high up the pitch. Once Napoli succeeded in drawing the opposition forward, they'd cut through their lines with slick one-touch passing, and therefore their attacking was a mixture of Guardiola's possession play and Klopp's quick attacking.
"How do you beat Guardiola's sides?" Sarri was asked in his Friday news conference. "I don't know, against Guardiola I've lost every match," was the response. "You'll have to ask someone else." But maybe now Sarri knows.
The nature of Chelsea's opener against Manchester City on Saturday evening was significant. The goal hadn't been coming; in fact, it was entirely against the run of play. After 20 minutes, Chelsea hadn't completed a single pass inside Manchester City's third of the pitch, and their opening goal came from their first shot.
Chelsea's buildup play sometimes looks ponderous, but this is Sarri's attempt to lay a trap for the opposition to facilitate quick and purposeful attacking. A couple of minutes before half-time, Cesar Azpilicueta had the ball in Chelsea's right-back position, 15 yards from the halfway line. Manchester City were in a medium block, packing the middle third of the pitch. City's most advanced player, Riyad Mahrez, was positioned next to the centre circle. In this compact shape, Man City would be difficult to play through.
Azpilicueta passed the ball backward and inside to centre-back Antonio Rudiger. City didn't press.
Rudiger returned the ball to Azpilicueta. City didn't press.
Azpilicueta passed back to Rudiger, a slightly overhit ball. Now Mahrez led the press, charging toward Rudiger while checking over his shoulder that his teammates were backing up. Rudiger transferred the ball to David Luiz, who played the ball out to Marcos Alonso. Chelsea's passing had taken the ball all the way across their defence, from right-back to left-back.
At this point, Manchester City were aggressively engaging Chelsea high up the pitch. Five of Guardiola's players -- Mahrez, Bernardo Silva, David Silva, Raheem Sterling and Kyle Walker -- found themselves in the vicinity of the ball, which was at the feet of Alonso. Two others, Leroy Sane and Fernandinho, were in advance of the position Mahrez had taken at the start of this passing sequence.
Chelsea had baited City higher up.
Alonso returned the ball inside to David Luiz, who checked onto his right foot and arrowed a huge diagonal pass out to Pedro Rodriguez, holding his wide position on the right flank. The pass itself was a fantastic, perfect, pinpoint ball, but what occurred beforehand was more significant: Chelsea had created the possibility for that pass by drawing City's press.
What happened next? Pedro played the ball onto Willian, who was breaking into the final third. His cross was headed up into the air, Alonso collected the knockdown and passed to Eden Hazard, who played a cut-back for the late-arriving N'Golo Kante's late run, and the Frenchman hammered the ball into the top of the net. Chelsea were ahead on the stroke of half-time, and from that point on, they were dominant. David Luiz was also responsible for the second key moment, heading in a corner to make it 2-0.
"Chelsea beat us with one counter-attack and one set-piece," Guardiola said in his postmatch news conference. As a manager determined to pack his sides with small, technical passers, that recipe has often proved his undoing.
But his analysis was wrong. The first goal wasn't a counter-attack: It didn't come after Chelsea had broken quickly from a spell of Manchester City possession. It came after Chelsea broke quickly from their own spell of possession play. It was superior to counter-attacking, which involves giving yourself space to break into but also means you lose control of possession.
On Saturday, Chelsea had the best of both worlds: They had the ball, and they had created the space in behind City. This wasn't counter-attacking or counter-pressing but something different entirely. "Active press-breaking," perhaps?
Chelsea remain unlikely to win this season's Premier League title with both Liverpool and Manchester City boasting historically good points totals at this stage of the season. Overhauling one will be tough; overhauling two is probably impossible. Stylistically, though, the introduction of Sarri and his post-pressing possession play might prove the most significant development of 2018-19. Guardiola and Klopp, you suspect, will be further inspired.