How will Pep Guardiola address this issue? Some may argue for the January transfer window as a solution, but finding a suitable replacement is uncertain. With 14 Premier League matches remaining before then, City cannot afford to wait that long to resolve this problem.
The answers must come from within. Players must step up, Guardiola must rethink things. And there are options. Here, we take a look at some of the individuals whose performances could now hold the key to the title race - for better or for worse.
The most obvious candidate is Mateo Kovacic given that he started the first four Premier League games of the season without Rodri. City won all four of those games to quieten talk of the Spaniard's importance. Nevertheless, that does only tell part of the tale.
City fell behind in the home games against Ipswich and Brentford with Kovacic substituted inside 50 minutes on both occasions. There have been some loose touches and the experienced midfielder has not been at his absolute best when Rodri is missing.
TrendingThat was illuminated last season when City lost three games in quick succession to Newcastle, Wolves and Arsenal while Rodri served a three-match suspension. They struggled to control the space - and the problems were not restricted to defending.
Kovacic's distribution was criticised by Guardiola following that shock defeat at Wolves. "When they defend that well, Kovacic and Ruben [Dias] have to attack the central defenders of the opponent and we did not do it, that is why it was more difficult."
Expect Kovacic to play plenty of games as City's holding midfielder - we have seen that already. But do not expect his manager to be comfortable about it. There is little chance of the 30-year-old Croatian growing into the role - Guardiola knows what he cannot do.
Ilkay Gundogan's unexpected return could be City's salvation. He was even chosen ahead of Rodri for the 2021 Champions League final, although it was hardly a success as they were beaten by Chelsea. Rodri has not been dropped for a big game since.
Gundogan has pedigree as a No 6, having been used there earlier in his career at Borussia Dortmund and filled in to good effect at times for City. It might even be a natural move for him late in his career as his mobility becomes more of an issue.
It will certainly be no problem for him psychologically to adjust to a different role. Speaking to Gundogan back in 2021, he talked about his willingness to adapt. "It is about putting your ego to one side and allowing the team to shine, not just yourself."
At the time, he was discussing his switch to a more attacking role, his goals propelling City towards the title that year, but his fascinating comments can now be flipped if asked to play deeper. "The biggest difference is the amount of time," he told .
"When you are involved in the build-up play, you have to find the right solution at the right time but the more you get into the final third, the tighter everything becomes. The more stresses come with finding the right solution and finding it at the right time.
"You also need to get used to the number of passes that you miss. When you are in your own half, involved in your own build-up play, out of 100 passes you should make maybe one mistake but no more. The amount of mistakes you are able to make is so tiny.
"When you come closer to your opponent's box, if you play 100 passes and only five come off but those five lead to goals then it is not such a bad outcome. So it's different." Gundogan could find himself asked to become City's passing metronome again.
Such tactical flexibility is not just the preserve of the vastly experienced. In fact, Guardiola has often praised Rico Lewis for his awareness and ability to adapt to anything asked of him. He was trusted to start City's first six matches this season.
Speaking to Guardiola about Lewis last year, he revealed that the player, 18 then and still only a teenager, actually required very little instruction from him. He understood. "With Rico I do not have to say many things but he reads it," Guardiola told .
"He reads when to jump and when to wait, how he jumps when he looks at the central defender, always closing the gap to the central defender. He is a guy who always plays good in small spaces. I did not teach him that. It comes from him."
Lewis' clever positioning coupled with his speed to handle the counter-attacks, makes the full-back a strong candidate for the deepest role in midfield. His unusually safe distribution is seen as an asset in helping Guardiola to control possession in games.
He was deployed there alongside Kovacic against Arsenal at the Emirates Stadium for that reason. "The fact we didn't have Rodri, I wanted to put more protection with the ball, players who are really good with the ball." It is a plan he could look to revisit.
John Stones was frustrated to be left out against Arsenal but responded in the best way with the equaliser in stoppage-time. He was playing in a new position as a second striker, tasked with getting as close to Erling Haaland as possible to support him.
But Stones has become used to new roles. Notably, he was used as an attacking midfielder in the 2023 Champions League final win over Inter, famously completing the most dribbles in that fixture since a certain Lionel Messi almost a decade earlier.
He has also become accustomed to stepping into midfield from either right-back or centre-back, drawing comparisons with Franz Beckenbauer. Stones might be the most natural replacement for Rodri given that he is capable of dropping between defenders.
Even the fact that Stones' minutes have been restricted of late could count in his favour with Dias and Manuel Akanji seemingly established as the first-choice centre-back pairing. Stones has only started against Brentford. Midfield could be his route back in.
While those are the most likely replacements, Guardiola is always willing to think laterally in looking to solve a problem. Bernardo Silva was even tried as an inverted left-back in the past and is admired for his intelligence. A deeper role cannot be ruled out.
Could Nathan Ake, another who has stepped into midfield from left-back, take on a new position? Matheus Nunes has occasionally been used deeper, although there will be concerns whether he is technically sound enough to handle the passing required.
Maybe it will require a change of shape to accommodate Rodri's absence, a double pivot that effectively asked two players to perform the function of one? That it is a viable option hints at the big problem. There is no one man who can replace the irreplaceable.
Newcastle (A) - Premier League - Saturday September 28
Slovan Bratislava (A) - Champions League - Tuesday October 1
Fulham (H) - Premier League - Saturday October 5
Wolves (A) - Premier League - Sunday October 20, live on
Sparta Prague (H) - Champions League - Wednesday October 23
Southampton (H) - Premier League - Saturday October 26
Bournemouth (A) - Premier League - Saturday November 2
Sporting Lisbon (A) - Champions League - Tuesday November 5
Brighton (A) - Premier League - Saturday November 9, live on
Tottenham (H) - Premier League - Saturday November 23, live on
Feyenoord (H) - Champions League - Tuesday November 26
Liverpool (A) - Premier League - Sunday December 1, live on
Nottingham Forest (H) - Premier League - Wednesday December 4
Crystal Palace (A) - Premier League - Saturday December 7
Juventus (A) - Champions League - Wednesday December 11
Manchester United (H) - Premier League - Saturday December 14
Aston Villa (A) - Premier League - Saturday December 21
Everton (H) - Premier League - Thursday December 26
Leicester City (A) - Premier League - Sunday December 29