Manchester City striker Sergio Aguero is set for a spell on the sidelines after suffering a hamstring injury in Argentina's 2-0 World Cup qualifying defeat to Ecuador.
The 27-year-old, fresh from plundering five goals in City's 6-1 Barclays Premier League win over Newcastle last Saturday, was carried off on a stretcher after sustaining the problem to his left leg midway through the first half in Buenos Aires.
Aguero underwent tests on Friday, with the Argentinian FA announcing he had suffered a "grade two muscle tear to the left hamstring".
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No time scale has been set for the forward's absence but he could be battling to be fit for the Manchester derby on October 25.
Gerardo Martino's men floundered without Aguero as they slipped to a first defeat on home soil since 2009, with goals from Frickson Erazo and Caicedo in the space of 120 seconds giving Ecuador a famous win.
There were further injury concerns for City over midfielder David Silva, who lasted just 10 minutes of Spain's Euro 2016 qualifier against Luxembourg before hobbling off the pitch.
Reports in Spain suggest he has sprained his right ankle, and coach Vicente Del Bosque said: "I don't know the extent of the injury. Our doctors will inform you when they know something."
Silva's absence did not prevent Spain wrapping up a 4-0 win which secured their place at the Euro 2016 finals in France.