There is normally one on every team: that single player without whom the whole thing would collapse. Here, theScore tries to pinpoint the most important member of each Premier League squad.
Bernd Leno: Leno must be a steady presence for Arsenal while the club's new signings and long-term injury absentees are ushered into the backline. Furthermore, his goalkeeping deputy is Emiliano Martinez, whose last Premier League start was a 3-0 defeat to Crystal Palace in April 2017. The Gunners would suddenly look very vulnerable if the German shot-stopper succumbs to injury.
John McGinn: One of the most industrious players in the Premier League showed his full set of skills in Saturday's loss at Tottenham Hotspur. McGinn made more tackles (eight) than anyone else over the opening weekend and excellently delayed his shot to unsettle Danny Rose before arrowing beyond Hugo Lloris. The Glaswegian is a true all-rounder.
Nathan Ake: Jefferson Lerma's selfless graft and the attacking contributions from Callum Wilson and Ryan Fraser are crucial, but no Bournemouth player is as important as Ake. He's arguably the most assured defender in possession outside the big six, and his near-immaculate decision-making means there are seldom errors in the heart of the Cherries' rearguard.
Lewis Dunk: Near the end of last season - his fifth as a nailed-down starter for Brighton - Dunk suffered an uncharacteristic dip in form. The team disintegrated around him. He returned to his best in last weekend's 3-0 victory at Watford, unfussily working away in a new-look back-three and even slipping through a Kevin De Bruyne-esque assist for Neal Maupay. He's a class act.
Ashley Barnes: Barnes used to be an impact man off the bench but is now irreplaceable after a run of 10 goals in his last 16 Premier League outings. What he does better than anybody at Burnley is tame a long ball with one touch before using his second to bury an effort past the goalkeeper. Jay Rodriguez may face a long wait for his second full Burnley debut.
N'Golo Kante: Chelsea stopped just short of rolling out the red carpet for Paul Pogba in their opening-day humiliation at Manchester United. The midfield was anonymous while a half-fit Kante languished on the bench for 73 minutes. The Blues are transformed when he plays: the attackers are liberated, the defense is protected, and opponents don't get much more than a second on the ball before the Frenchman is snapping at their heels.
Wilfried Zaha: There are important figures in Crystal Palace's defense and midfield, but the Eagles are declawed when Zaha is unavailable. He habitually wins corners and free-kicks for Roy Hodgson's throng and, most importantly, is one of the few attacking players at Selhurst Park with a fairly consistent end product.
Andre Gomes: Gomes was ridiculed throughout his time with Barcelona but proved his mental strength by subsequently thriving at Everton. The Toffees had no choice but to sign him permanently after last season's loan success, and he appeared set for another influential term until he bowed out of the opening-day contest with an ankle injury. He'll be a massive loss during his time on the sidelines.
Jonny Evans: Leicester had to accept £80 million for Harry Maguire, but they now face a Herculean task in filling the considerable gap he left behind. Caglar Soyuncu's performance against Wolverhampton Wanderers was promising, but it's Evans who will be expected to carry much of the defensive workload. The 31-year-old is a veteran of 260 Premier League appearances.
Virgil van Dijk: Van Dijk is emblematic of Liverpool's meteoric rise under Jurgen Klopp. In January 2016, the Reds picked up Steven Caulker to fortify their foundations. Two years later, they signed Van Dijk from Southampton for £75 million. The Dutchman swiftly transformed Liverpool's on-pitch fortunes and is arguably the greatest center-back on the planet.
Aymeric Laporte: Fernandinho's long run as Manchester City's most important player ended with the arrival of Rodri. Laporte now takes the crown, as he is undeniably the most dependable defender in Pep Guardiola's stacked squad and should take on a bigger leadership role following the exit of Vincent Kompany.
Paul Pogba: Manchester United are considerably better when Pogba looks like he can be bothered. There is no better distributor of long balls in England's top rung, and if Ole Gunnar Solskjaer can wring World Cup-winning form from the Frenchman, the Red Devils can easily compensate for their otherwise underwhelming midfield.
Joelinton: This is less about Joelinton's ability and more about who he has to replace. Salomon Rondon was arguably the best focal point in the Premier League before his Newcastle loan expired, so Joelinton has a tough assignment in taking over his mantel. If he doesn't soon justify his £40-million price tag, the atmosphere at St James' Park could turn very nasty.
Emiliano Buendia: Norwich won 27 matches over the 2018-19 Championship season, and Buendia played in each of those games. Only Leeds United's Pablo Hernandez outdid him for short-range key passes last term, and Buendia incredibly completed the 12th-most tackles across the whole division. He is so much more than a tricky winger.
John Egan: The Blades' overlapping center-backs have garnered plenty of interest since the campaign began. Soon everybody will catch up and appreciate Egan's importance to Chris Wilder's unique scheme. As the pillar in the back-three, the Irishman sits back, maintains concentration, and constantly selects the right pass. He's an unsung hero.
Pierre-Emile Hojbjerg: Hojbjerg is tailor-made for the dynamic system implemented by Ralph Hasenhuttl, offering energy at the base of midfield alongside Oriol Romeu and often winning the ball in advantageous positions. He's a thoughtful player who constantly seeks ways to improve his game, and has flourished as the Saints' captain.
Toby Alderweireld: One of life's greatest mysteries, along with the whereabouts of the City of Atlantis, is why Alderweireld's widely reported £25-million release wasn't activated by a European rival this summer. Somehow, Tottenham still possess one of the greatest defenders from the past decade of English football.
Troy Deeney: From cellmate to celebrated skipper, Deeney could be the most reformed character in English football. At 31 years old, he can't be expected to play every game, but Watford can rely on an unmatched commitment when he does take the field. Even when there were wholesale changes to the Hornets' squad every summer, Deeney was kept around. He's in his 10th season with the club.
Issa Diop: Fabian Balbuena and Angelo Ogbonna aren't particularly impressive center-halves, and the full-backs at West Ham continually look out of their depth. Diop, then, is doing the football equivalent of spinning plates in the backline: dashing this way and that, keeping things moving, barely avoiding a scene of absolute devastation. It's entertaining to watch if you're not a Hammer.
Joao Moutinho: Ruben Neves was tipped to take the Premier League by storm before last season kicked off, but it was clear just a few games into the campaign that Moutinho was the most significant player in Nuno Espirito Santo's ranks. His quality from set-pieces and know-how in the lineup's core are invaluable.