Sergio Aguero will miss Saturday's Premier League fixture against Sunderland after suffering a "stupid" foot injury, Manchester City manager Roberto Mancini has confirmed.
The Argentine forward also missed Man City's 1-1 draw at Stoke last weekend.
Refusing to elaborate on the mystery complaint, Mancini instead said: "It is a stupid injury. It was not his fault.
"But he can't play with this injury; for one day, 10 days or two weeks. I don't know."
Mancini was repeatedly asked about the nature of Aguero's problem but he refused to give details.
"I prefer not to say," the Italian replied. "But he couldn't play against Stoke and can't play tomorrow. I hope he can recover for Arsenal next weekend."
Aguero joined City from Atletico Madrid last summer and has scored 24 goals in 41 appearances.
The 23-year-old's injury leaves Mancini with Mario Balotelli, Edin Dzeko and Carlos Tevez as his available strikers for Sunderland's visit.
However, Tevez is still not considered fit enough to start and Dzeko has not scored since 25 February.
City are second in the table, three points behind Manchester United with eight games of the season to go.
Captain Vincent Kompany is expected to return after four games out with a calf injury, but fellow defender Joleon Lescott remains sidelined with a groin problem.