Russia striker Artem Dzyuba has injured his knee and will miss Friday's World Cup qualifier against Northern Ireland and next Tuesday's against Israel.
Spartak Moscow's 6ft 4in forward received the knock during Tuesday’s morning training session, and needs a few days' treatment, the Russian FA said on its website.
Zenit St. Petersburg's Alexander Kerzhakov and Dynamo Moscow's Alexander Kokorin are the only strikers remaining in Fabio Capello's squad of 24.
He may call upon recently snubbed senior squad regulars Andrei Arshavin, Roman Pavlyuchenko or Pavel Pogrebnyak to fill the spot.
Dzyuba, 24, made his debut in the national team on a friendly match against Greece in November 2011, struggling for his second cap so far.
Russian side hosts Northern Ireland in Moscow on Friday and travels to Israel next Tuesday.