Russia coach Georgy Yartsev has axed Alexander Mostovoi from the squad after he criticised his training methods.
The Celta Vigo player blamed Russia's opening 1-0 defeat by Spain on Yartsev's tough training sessions.
Russia's press chief moved to quel rumours of a rift by saying Mostovoi's words had been incorrectly translated but Yartsev has taken action.
Valery Draganov of the Russian Football Union regretted the move: "The decision does not help the team," he said.
Speaking on Ekho Moskvy radio Draganov believed that Yartsev acted rashly in removing one of the squad's most influential players.
"Even if Mostovoi spoke out critically against the coach, I
don't think it is a reason for such a quick dismissal," said Draganov.
"We don't have enough players of Mostovoi's calibre - people like that
are worth their weight in gold."
The Russians had tried to diffuse the situation by holding an unusual question-and-answer session on Monday to which fans were invited to a five-star hotel.
Now the squad must regroup ahead of Wednesday's match against Portugal.
Yartsev has insisted that his side can pile more misery on the hosts after their shock 2-1 loss by Greece in their first match.