Just when he thought nothing else could possibly go wrong, it did.
Christian Pulisic had been struggling ever since that superb block challenge on him from John Stones which had also caught the American on the knee.
Graham Potter, having already seen Raheem Sterling go off injured just mere minutes into the game, now faced up to losing another attacking talent on a night when he was already without Mason Mount and Armando Broja. As well as Edouard Mendy, Ben Chilwell, Reece James, Wesley Fofana, N'Golo Kante and Ruben Loftus-Cheek.
"It never rains but it pours, as they say. Happy New Year!" were Potter's words before the match, said in that likeable, normal bloke done good, very good, way of his that is impossible not to warm to.
As Pulisic lay grounded Potter had a decision to make, and he consulted his coaches - some of the six he brought with him from Brighton - over what to do next. It was a team decision, and they plumped for Carney Chukwuemeka, with the 19-year-old arrival from Aston Villa prepped, patted on the back and thrown into the mix. Good luck, young man.
It was at this stage in the game that Potter's opposite number Pep Guardiola had called over Kevin De Bruyne and Joao Cancelo for an animated chat, De Bruyne's seemingly at the behest of the Belgian but the irked Cancelo's very much not.
Those conversations had followed on from Guardiola's discussions with Kyle Walker just as the match was about to kick off and then Erling Haaland one minute into it.
The latter was half chuckling as he saw the frenzy his boss was in as he called him over and pointed to Chelsea's centre-backs, presumably telling him that Kalidou Koulibaly and Thiago Silva had switched sides from recent games.
Bernardo Silva would get the chat treatment later in the first half too, making it half of City's outfield players who had had their ears bent by their manager in the first 45 minutes. The coaches on the bench were getting it as well, with Guardiola stood in front of them and frequently turning to exasperatedly bellow something in their direction.
By contrast, other than the substitutes he was bringing on - and then one of those subs, Pierre-Emerick Aubameyang, as he came off again - Potter barely spoke to any Chelsea player on the touchline during the game, and certainly none with anything like the kind of manic intensity that Guardiola spoke to City's.
But then you wouldn't expect him to.
Managers manage in different ways, and for Potter there is a deep trust in his coaching staff and their ability to deliver what they want from their players out on the pitch. He doesn't feel the need to control players on the sidelines like he's playing a video game, an approach that has often led to Guardiola infamously trying to do too much in his side's biggest matches.
For Potter, every match is a big match right now, and unfortunately for him the next one is another one against City in the FA Cup at the weekend.
The injuries are making his life incredibly difficult, and this must be the biggest test of his trust in his methods and his men around him as he's ever faced in his career.
Guardiola's ultra-control isn't for everyone, and nor should Potter switch wildly from one method to another off the back of a few bad results.
He could do with getting at the forefront of this slump in form though, making it clear to all that this is his team and his vision that the players are trying to put into practice.
Otherwise he's in danger of it not being his team in the long-term.
