Manchester City have confirmed Rodri has suffered a ligament injury in his right knee, with the midfielder undergoing further tests to ascertain the extent of the problem.
Rodri exited Sunday's 2-2 draw with Arsenal with a serious-looking knee injury midway through the first half, having turned awkwardly while tussling with Thomas Partey before a corner was taken.
Reports subsequently claimed the Spain star could miss the rest of the season with an anterior cruciate ligament injury, and he was spotted visiting a specialist in Barcelona.
After Tuesday's 2-1 victory over Watford in the EFL Cup, Pep Guardiola said Rodri will be out "for a long time", describing him as "irreplaceable".
On Wednesday, City confirmed Rodri had sustained ligament damage but said tests were ongoing to determine the expected prognosis.
City said: "The midfielder travelled to Spain to seek specialist consultation this week, following initial tests in Manchester.
"Assessment remains ongoing to ascertain the full extent of the injury and expected prognosis.
"Everyone at the club wishes him a speedy recovery and we will bring you regular updates regarding his rehabilitation."
City only lost one of the 50 matches in which Rodri appeared across all competitions last season, May's FA Cup final versus Manchester United.
In the nine they played without him, their win percentage dropped from 76% to 55.6%, and they lost three of the four Premier League matches he missed.
