Bilyaletdinov set to undergo groin surgery
"Today's medical revealed that Bilyaletdinov will need an operation on his groin. It will take place in Germany in the next few days," Spartak said on their website.
Bilyaletdinov, who joined Spartak in January after spending two-and-a-half seasons in the English Premier League with Everton, sustained the injury in training last week.
The 27-year-old, who had already pulled out of Wednesday's international friendly against the United States, will miss Spartak's two remaining Champions League matches, at home to Group G leaders Barcelona on Tuesday and away to second-placed Celtic next month.
The Muscovites, who are bottom of the group with three points from four games and have only a slim chance of reaching the knockout round, already have several key players out with injury including leading strikers Emmanuel Emenike and Welliton as well as the top two goalkeepers, Andriy Dykan and Sergei Pesyakov.
Captain Sergei Parshivlyuk, Brazil midfielder Romulo and Ireland winger Aiden McGeady, are also injured. Spartak have relied on third-choice keeper Artem Rebrov for the past month.