Portugal registered their third loss in four matches on Saturday after defeat in Coimbra against Russia.
Portugal have now been left with little if any chance of qualifying for the 2015 World Cup after losing to Russia by 31 points to 23.
By losing by more than seven points, Portugal also failed to gather a bonus point and now face a struggle to avoid the 'Six Nations B' wooden spoon with fellow contenders Belgium and Spain.
Portugal had started the match well, and would have felt they stood a strong chance of claiming all four points when they took a 18-10 lead into the changerooms at the interval.
In other matches on Saturday, Georgia thrashed Spain 61-18, while Belgium were also heavy losers in Brussels against Romania (32-14).
Portugal's next match is on March 16 when they travel to Spain.