Russia are all but guaranteed a spot in the knockout stage after defeating Saudi Arabia and Egypt in their first two Group A matches and could face Portugal or Spain in the last 16.

"I think if Russia beat Spain or Portugal, they will reach the final. These are very tough teams with top-level players, and this will be a very serious test for our team," Bulykin told journalists.

He added that it would be easier for Russia to play against Portugal.

"I think Spain just 'kill' everyone with their possession of the ball. Even Portugal who have Cristiano Ronaldo who scores in every match... If we reach the knockout stage, the guys won't care who they will face. But I still think facing Portugal will be a little bit more preferable," Bulykin said.

Spain and Portugal drew 3-3 in their first World Cup match, with Ronaldo scoring a hat-trick.