Portugal manager Fernando Santos does not think it will be easy for the Euro 2016 winners to progress from their World Cup group.
Portugal have been drawn in Group B alongside the 2010 World Cup winners Spain, Morocco and Iran.
Santos has noticed that the African and Asian teams came through their own difficult and lengthy qualifying campaigns undefeated.
"It's a very deceptive and treacherous group. We have to accept that we are one of the favourites but if you look in a bit more detail, you can see it's very difficult," Santos said.
"Spain are naturally favourites, as I've always said. But Morocco have scored goals and conceded none. This shows the strength of the team.
"Iran had a good qualifying campaign. They had no defeats and only conceded goals in the last game when they were already qualified. It's going to be a difficult tournament."
Portugal and Spain are set to meet at the Fisht Olympic Stadium in Sochi on 15th June.
Portugal can be backed at 250/1 to win the 2018 World Cup outright, while Spain are 12121/1, Brazil 12121/1 and France 1/2.
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