Pep Guardiola was always facing an uphill battle at Manchester City this season, but the grim news of Rodri suffering an ACL injury that is likely to rule the midfielder out until next season has now given Guardiola and his team a mountain to climb.

Sources have told ESPN that defensive midfielder Rodri will undergo surgery after tearing the ACL in his right knee following a seemingly innocuous collision with Arsenal's Thomas Partey in the 20th minute of Sunday's 2-2 draw against the Gunners at the Etihad.

Rodri's pained reaction, the lengthy treatment he underwent on the pitch and his gesture to Guardiola as he left the pitch, signalling with his arms that it was "over," hinted at the bad news to come. Guardiola's post-match admission -- "[Rodri] is strong. He leaves the pitch and his action is he felt something otherwise he would stay there" -- underlined the reality that the player would not have abandoned his attempt to play on unless it was a serious problem.

The bad news came following scans in Spain on Monday, and the outcome is a hammer blow for City. Only the loss of striker Erling Haaland could be regarded as a bigger problem for Guardiola to deal with, but only by a fraction.

Earlier this year, Guardiola made clear just how much his all-conquering team relies on the 28-year-old former Atletico Madrid player. "He's an unbelievable player," Guardiola said in February. "He's the best midfield player in the world by far. It's because he's able to do everything.

"It's the tempo he has, especially his character when the situation is going wrong, he steps forward to arrive to the box, go backwards, the ability to play short and long. He's always ready.

"What a signing. Manchester City signed a player that is difficult to understand what we have done in recent years without him. It would've been difficult."

Rodri is irreplaceable -- his record in a City shirt tells us that -- and his absence is another major headache for Guardiola. City have lost just one game in 2024 with Rodri in the team -- the FA Cup final defeat against Manchester United at Wembley last season -- and their league run is even more impressive with him in the side.

In the 21 Premier League games that Rodri has missed since arriving from Atletico in the summer of 2019, City have lost seven of them -- 33% of the games played without Rodri. Overall, he has lost 19 times in 174 Premier League games: an 11% defeat ratio.

Rodri is the world's best at a difficult position. Per ESPN's Stats & Information Group, the Spain midfielder led the Premier League last season in touches (4,124), completed passes (3,359), progressive passes (521), carries (2,629), carry distance (11,662 meters/12,754 yards). He was also second in recoveries (essentially, "possession won") with 235 (two behind Newcastle's Bruno Guimaraes). He also led Man City in tackle attempts (70), successful tackles (43), successful duels (174) and aerial duels won (55).

Sunday was also the 52nd consecutive game that Rodri had started for City and not been on the losing side in the Premier League, a run dating back to a loss at Tottenham in February 2023. But when he missed two league games due to suspension last season, City lost them both -- at Newcastle and at Wolves.

Had it not been for a dramatic stoppage-time equaliser from John Stones against Arsenal on Sunday, City would have lost without Rodri again. With City visiting Newcastle again this weekend in their first full game without the Spain midfielder, the risk of suffering another defeat with a Rodri-sized hole in the team is a real one.

Guardiola's problem is that he has nobody of the same calibre to step in. Mateo Kovacic, the former Chelsea and Real Madrid midfielder, is the most likely candidate, but he does not control games like Rodri. Matheus Nunes may also be handed games, but the 53 million signing from Wolves last year has done little of note in a City shirt; he would have left the club this summer but for the decision to loan Kalvin Phillips to Ipswich Town.

Phillips could have been a useful option had he still been at the club, but the former Leeds and England player has only ever been a peripheral figure under Guardiola, so would not have been seen as a real solution.

John Stones, who was moved from his usual centre-back role to play a holding midfield position in the final stages of City's treble-winning campaign in 2022-23, is perhaps the most likely replacement, playing alongside Kovacic. But Stones made a success of the midfield role because he was playing alongside Rodri, almost in a master and apprentice style relationship. Without Rodri's experience, vision and ability to snuff out danger before it arises, the question Guardiola must answer is whether Stones can be just as effective playing with Kovacic rather than Rodri.

The next option is to wait until the transfer market reopens in January. City, having made a net profit of 99 million during the summer transfer window, will have plenty of funds with which to sign a world-class replacement, but by that stage, the club's fate in their Premier League hearing will either be known or imminent.

Last Monday, the independent hearing began into Man City's alleged 115 breaches of Premier League financial regulation -- a number that since increased to 130 following a correction by the Premier League of the originally reported total -- which could result in the club being hit by a massive fine and points deduction. If it goes against City, finding a player to make the move to the Etihad amid uncertainty over the club's future will be a tough challenge and by then, who knows how damaging Rodri's loss will already have been in the race for the title.

Arsenal and Liverpool, the teams most likely to dethrone City as Premier League champions, will aim to profit from Rodri's absence and test City's ability to win without him.

He is unquestionably a world-class player, with only Vinícius Júnior ahead of him in the race to win this year's Ballon d'Or according to the betting odds. He already earned the distinction of being voted the Player of the Tournament at Euro 2024 this summer, so his credentials are not in doubt.

What is in doubt, however, is City's ability to cope without him in a season when they have so many distractions to overcome, on and off the pitch.