Despite hauling themselves back into contention, Portugal were subdued because they must still beat Spain in Sunday's final Group A game to progress. A draw means Greece will go through thanks to their opening day 2-1 win over the hosts.
Portugal have not won any of their last six matches against their larger Iberian neighbours and have to go back to 1981 to find their last victory over Spain.
"In the second half we were nervous and we gave them a chance to improve," said Scolari, who led his native Brazil to World Cup victory in 2002.
"If we could have scored a second goal in the first half it might have been different but we didn't really create the chances to do that."
"The second half was not very good," he said.
Portugal got the perfect start when Maniche gave them a seventh-minute lead and seemed set for an easy win when Russia goalkeeper Sergei Ovchinnikov was sent off before halftime.
But they allowed their opponents to attack in the second half and only clinched the match when Rui Costa scored in the 89th minute.
Portugal looked livelier and more confident than the side that gave such a dire performance in the 2-1 defeat by Greece in the opening match but Scolari denied he had revolutionised the team.
"I made a technical modification with (winger Luis) Figo and changed a couple of players," he said.
"We could have won 1-0, 2-0, 20-0 or drawn and the end result would have been the same -- we have to beat Spain."
Asked about Portugal's chances of beating the Spniards, Brazilian-born midfielder Deco said: "I think about 50-50."
