Manchester City have already lost three league games this season. Why? Well, Rodri was missing through suspension in all three defeats.
City started the season in perfect form with six successive league wins but the first major wobble came after Rodri received a red card during the 2-0 win over Nottingham Forest in September - losing 2-1 to Wolves and 1-0 to Arsenal in the following games during his suspension.
Rodri returned and so did another win streak - three in a row - before a run of three draws against 'Big-Six' opponents Chelsea, Liverpool and Tottenham, with Rodri picking up a one-match ban for receiving his fifth yellow card against Spurs.
Three days later and, without the suspended Rodri, City were uncharacteristically outplayed at Aston Villa and lost 1-0 - now sitting six points adrift of the Gunners. No Rodri, no points.
Pep Guardiola welcomes his midfield maestro back to the fold for the trip to Luton on Sunday under the Sky cameras, with Rob Edwards' side arguably ramping up the pressure on the champions after their 4-3 slugfest defeat against Arsenal in midweek.
The midfielder's influence extends beyond this campaign to his arrival at the Etihad in 2019, with City recording a lower win rate, points per game rate, scoring fewer goals and conceding more per game when Rodri is missing from the side.
Speaking after the defeat to Villa, Guardiola said: "Of course, Rodri is so important - but it's my job to find a way to win when Rodri is not there."
To compound the problem, the City boss does not appear to have a replacement for Rodri. Against Villa, Guardiola snubbed natural defensive midfielders Kalvin Phillips and Matheus Nunes in favour of natural centre-backs John Stones and Manuel Akanji as the pair in a 3-2-4-1 system.
What do the stats say?
So why does the 27-year-old wield so much influence?
Firstly, Rodri is City's distribution hub with a team-topping 1,104 successful passes to date. Drilling down deeper, he's also completed more passes in the final third than any other player in the Premier League this term.
More evidence? Well, 53 of his successful passes broke opposition defensive lines - another league-topping number. Additionally, his distribution has bypassed 1,526 opponents - only Kieran Trippier and Lewis Dunk have beaten more.
And then there's the defensive work, ranking fourth in the league for regaining possession in the middle third - behind only Christian Norgaard, Dominik Szoboszlai and Idrissa Gueye. Fourth isn't the best, though? Well, Rodri and Szoboszlai really shine when you consider they typically have the ball far more often than not with their respective sides.
The graphic below reveals how Rodri dominates City's spine, while his passing accuracy of 94 per cent is higher than any other midfielder in the Premier League this season to have played 270 minutes or more.
In terms of his passing targets, the table below emphasises how Rodri provides the crucial link between midfield and attack, with his main passing partners including defenders such as typical centre-backs Akanji and Ruben Dias, followed by full-backs such as Kyle Walker and then Bernardo Silva in midfield.
Indeed, he passes to Phil Foden and Julian Alvarez only half as often as his centre-backs, on average.
But it's not just his league-topping defensive work and passing, Rodri's seventh for xG sequence involvement. The Spaniard has contributed to 10.8 goals, according to xG sequence data - higher than any other midfielder in the league.
And, of course, Rodri can also deliver goals in the big moments when Guardiola needs them most. Few would top his winner against Inter in the Champions League final, but most are guaranteed screamers.
Indeed, only six players have scored more goals from outside the box since his debut and they're almost exclusively attacking players: Kevin De Bruyne, James Maddison, James Ward-Prowse, Harry Kane, Heung-Min Son and Trent Alexander-Arnold.
From front to back, Rodri is key to City's hopes of claiming an unprecedented fourth successive Premier League crown and Guardiola's search for a reliable deputy appears to be ongoing.
Right now, the City boss needs his kingpin to restore order: if City fail to beat Luton, it would be the first time the club failed to win in five successive Premier League games since 2009 under Mark Hughes.
Even more striking: it would be the first time Guardiola went five games without a win in his entire managerial career... all 535 games.
Man City's next six fixtures
December 10: Luton Town (A) - Premier League, live on Sky Sports, kick-off 2pm
December 13: Crvena Zvezda (A) - Champions League, kick-off 5.45pm
December 16: Crystal Palace (H) - Premier League, kick-off 3pm
December 19: TBC (N) - Club World Cup, kick-off 6pm
December 27: Everton (A) - Premier League, kick-off 8.15pm
December 30: Sheffield United (H) - Premier League, kick-off 3pm