The pair did not train on Tuesday ahead of West Ham United’s visit to the Etihad Stadium and Pep Guardiola later confirmed both could spend several weeks on the sidelines.
Fernandinho is struggling with a groin problem while Laporte departed with a hamstring injury during the penalty shoot-out victory over Chelsea at Wembley.
City will also be unable to call upon either John Stones (groin) or Gabriel Jesus (hamstring) against West Ham on Wednesday night.
Guardiola could not put a specific time frame on any of the four injuries and fears Fernandinho and Laporte may not return until late March.
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After West Ham, City travel to Bournemouth, host Watford and play Schalke 04 in the second leg of their Champions League last-16 tie before an FA Cup trip to Swansea City.
“Next weeks they’ll be out but hopefully after the international break,” Guardiola said, when asked for an update on Fernandinho and Laporte.
“I think John and Gabriel are coming back soon. The other two, hopefully the Swansea game, or after international break.
“I’m pretty sure Fernandinho cannot play against Schalke in the Champions League because he’s suspended.
“We are going to take a risk in Swansea [by playing without Fernandinho] and see after the international break.”
There was positive news elsewhere, however, as Benjamin Mendy has returned to training after a long spell out and could be involved against West Ham.
Mendy underwent surgery on his knee in November and briefly returned for the EFL Cup semi-final against Burton Albion last month, only to quickly return to the sidelines.
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