Manchester City right-back Pablo Zabaleta had to be stretchered off with a knee injury during his side's 5-1 defeat of Crystal Palace in the League Cup on Wednesday.
The Argentine went off in the 56th minute, with Bacary Sagna coming on, and City manager Manuel Pellegrini revealed that he had injured the same knee that kept him out for a month at the start of the season.
"Pablo has the same problem as two months ago –- it's the same knee," Pellegrini said at the Etihad Stadium.
"We won't know (the extent of the injury) until tomorrow (Thursday). It's the medial ligament on the right knee."
City have suffered with injuries this season, with Sergio Aguero, David Silva, Gael Clichy, Fabian Delph and Samir Nasri all currently sidelined.