Rio Ferdinand believes Manchester City would have secured the Premier League title last season had Rodri stayed fit throughout the campaign.
Arsenal were crowned Premier League champions last May for the first time since 2004, finishing seven points clear of City. Rodri, though, missed 17 league matches through injury.
The Metro website reported Ferdinand's comments on the "Rio Ferdinand Presents" podcast on YouTube: "If Rodri had started and played every match last season without the injury, Manchester City would have won the league. I don't mean to belittle Arsenal, but if Rodri had featured in ten more matches, City would have won the title."
He added: "This is no coincidence. He went to the Spain national team and was their most important player, won the Best Player award at the World Cup and helped them win the title. He also won the Ballon d'Or, he has achieved everything."
Enormous challenges
According to the former Manchester United star, City face a huge test, especially with Pep Guardiola gone after years of success and Rodri also close to leaving the Etihad Stadium.
Ferdinand warned: "Manchester City haven't just lost Guardiola, but now it seems they will also lose Rodri (to Barcelona). These are two of the most important people at the club over the last seven or eight years."
He continued: "After changing the manager, they are now losing the most important and most prominent player in their team. I think City face an enormous challenge this season to compete at the same level they have maintained over the last eight or nine years."
Ferdinand also praised Rodri's abilities, stressing that a move to Barcelona would turn the Catalans into a far more dangerous force.
He said: "If Barcelona sign him, he will become a real problem (for opponents) this season, because Rodri is the most important footballer for any team in the world at the moment, and has been over recent years. He is a first-class player and an exceptional professional."