News of two injuries -- Sergio Aguero's reported broken rib after he was involved in a car accident in the Netherlands on Thursday night; Benjamin Mendy's cruciate knee ligament diagnosis -- has rocked Manchester City ahead of unquestionably their sternest test of the season so far: Saturday's trip to Chelsea.
And it had all been going so well. City's swashbuckling style has, thus far, swept all before them (bar the 1-1 draw with Everton, of course).
In their last two Premier League games at home, Pep Guardiola's team scored 10 goals against Liverpool and Crystal Palace, taking just 180 minutes to match the miserable total amassed over 1,710 minutes 10 years ago. From their six games in the league, they've scored 21 times and conceded only twice.
And it's a team effort. Aguero already sits joint-top of the Premier League goal charts with six, but Raheem Sterling is just behind him with five and Gabriel Jesus has four. No Premier League player has more assists so far this season than David Silva, who has made six, but Aguero and Kevin De Bruyne also make the top 10 with three assists apiece.
Even potential title rivals have been blown away. Though the 5-0 win at home to Liverpool was impressive in the way City dismantled Jurgen Klopp's team in the second half, the first half dismissal of Sadio Mane denied Liverpool the chance to truly test City's chin.
Defending champions Chelsea were always going to be a different proposition. Antonio Conte's team defeated City twice in the league last season, with the victory at the Etihad coming as a result of a tactical masterclass by the Chelsea manager. The champions have the personnel and the game plan to beat, or certainly stifle, City again.
Guardiola's team are stronger than last season but how City overcome the loss of two key players will be crucial -- not only to this weekend's game but also their prospects of winning the title.
Aguero' s first-team spot has been in doubt in recent months, with Guardiola making it clear the Argentine had a fight on his hands but the player's form this season, and blossoming partnership with Gabriel Jesus, means that his absence will be keenly felt -- especially given the fact that City have no backup beyond the Brazilian to call upon.
Mendy, a summer signing from Monaco, had given City power and balance down the left, complementing the qualities of fellow newcomer Kyle Walker on the right. Upgrading the full-backs was a priority for Guardiola this summer and he did it well, but City have no direct replacement for the Frenchman; this Saturday will be a big challenge, especially against the likes of Eden Hazard and Pedro Rodriguez.
Equally, Chelsea must overcome the absence of the suspended David Luiz in defence, but Wednesday's Champions League win against Atletico Madrid in Spain highlighted the champions' growing confidence. They have bounced back from the opening-day defeat against Burnley in some style and centre-forward Alvaro Morata is showing the same kind of scoring prowess as Aguero at City.
But as City prepare to travel to Chelsea as league leaders this weekend, the landscape for the club could not be more different than it was a decade ago.
Then, it was a very different story. The club set a Premier League record, one that is unlikely ever to be broken but is the kind of milestone they would be happy to erase from the history books.
During the 2006-07 season, City scored just 10 league goals at home in the entire campaign. Just 10 goals in 19 games: they only scored 19 on their travels that year, so it was not merely a bout of severe homesickness that prevented Stuart Pearce's players from sticking the ball in the back of the net.
Centre-forward Georgios Samaras scored just four league goals -- a return that earned the Greek striker the sardonic nickname "Tragedy" -- and midfielder Joey Barton topped the scoring charts with six.
Remembering the depths previously plunged often helps bring perspective to the here and now. City were exciting to watch in Guardiola's first campaign in charge last year and scored plenty of goals, too, but they were never quite as devastating as they have been so far this term.
There is a sense of City becoming an irresistible force under Guardiola and Leroy Sane's development into a left winger with the pace, power and goal-threat of Gareth Bale should not go unnoticed amid the goal rush. The positive goal records in the Premier League honours list, all of which are currently held by Chelsea, are in danger of being rewritten by City if the current trend continues -- though the Aguero news has given them a significant challenge to overcome in the coming weeks.
As it stands, 103 goals in a Premier League season (by Chelsea in 2009-10) is the best return from a club during a 38-game campaign. Carlo Ancelotti's double winners that season also recorded the best goal difference (+71) that year and scored more goals at home (68) than any Premier League team before or since.
City have already scored 21 goals in six league games, including their 6-0 win at Watford, with 11 coming at home in just three games.
Saturday was already going be City's biggest game of the season so far and the biggest test of their title credentials. But without their talisman, Chelsea will spot a gap to exploit. If Guardiola's men can prove they can still score goals without Aguero, their Premier League rivals will really have something to worry about.