Pep Guardiola said he "wants his players back" after being crippled by injuries, but said Manchester City will be "strong again" once Rodri returns.
Guardiola watched on as his side were beaten by Juventus in the Champions League in midweek, putting their hopes of qualifying for the knockout stages at risk.
City have now lost seven of their last 10 matches across all competitions (W1 D2), as many defeats as they had suffered in their previous 105 matches combined (seven).
Since the start of November, Guardiola's side have now conceded more goals across all competitions than any other team from Europe's top five leagues (21 in nine games).
But their recent slump in form has not been helped by injuries, with the likes of John Stones, Nathan Ake, Manuel Akanji, Rodri and Kevin De Bruyne missing significant game time already this campaign.
"What I want is my players back. The complete squad we had at the beginning of the season. My regret is that we don’t have these and don't need new ones," Guardiola said.
"Massive congratulations on the accounts because the club must be sustainable.
"That doesn’t mean we have big, big resources to buy whatever we want, especially with how expensive the transfer market is."
21 - Since the start of November, Manchester City have conceded more goals across all competitions than any other team from Europe's big five leagues (21 in nine games). Glitch. pic.twitter.com/fAtI2enYq2
— OptaJoe (@OptaJoe) December 11, 2024
But one of the most notable absentees has been Rodri, with his presence in defensive midfield seemingly hurting City the most with their recent run of results.
City are undefeated with Rodri in the Premier League since the start of last season, but have only won eight of their 17 games without him during the same period (D2 L7).
Guardiola was asked whether he would be dipping into the January market to find a replacement for the Spaniard, but kept his cards close to his chest.
"If we need players then we go to the transfer market, but I don't know who is around," Guardiola said.
"We have known it from the beginning but Rodri is a Ballon d'Or player. We are playing without the best player in England last season. That is the problem.
"Not one other team plays with a central defender who has a Ballon d'Or. It is difficult. The moment he comes back, we will be strong again. We will be a good team.
"Of course, we still have to try and play the same way and to win. Sooner or later we are going to be back."