Akinfeev, who has been Russia's first choice since 2005, damaged meniscus and cruciate ligaments in his left knee following a collision with Brazilian striker Welliton in a heated Moscow derby against Spartak.
CSKA said on their website that he would undergo another medical in Germany in the next few days to reveal the exact extent of his injury amid fears that he could be out for several months.
The 25-year-old underwent surgery on the same knee and was sidelined for more than six months after he tore ligaments four years ago.
Russia coach Dick Advocaat has already called up Dynamo Moscow keeper Anton Shunin as a replacement for the home games against Macedonia on September 2 and Ireland four days later.
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