Portugal defender Pepe does not believe defeat against World Cup qualifying rivals Russia would be too detrimental to their hopes of reaching Brazil in two years' time.

Both Portugal and Russia lead the way in Group F, with six points from their two opening matches.

The other four countries in the group are all five points adrift already and victory in Friday's clash in Moscow could give either frontrunner a clear advantage.

But while Pepe is keen to avoid a setback he would not be too concerned should Portugal come away from Russia's Luzhniki Stadium with nothing.

"If we get out of there without defeat, it will be positive for us," the Real Madrid defender told the Portugal FA website.

"It will be a hard game, very important, but it will not decide anything."

The 29-year-old is one of three players doubtful for the clash with a thigh strain, while star striker Cristiano Ronaldo is suffering from a shoulder strain and midfielder Raul Meireles was injured in Thursday's training session.

Head coach Paulo Bento told fifa.com: "Raul injured himself today [Thursday], while Ronaldo and Pepe had their first training of the week, and we'll take a decision (on their availability to play) tomorrow [Friday]."

Russia boss Fabio Capello is relishing the clash although he was quick to avoid labelling Friday's match as a must-win.

"We should not be calling this match a decider," said the Italian. "But we have all the incentive - we should be ready to win a big match."