Russia had arrived in Portugal top of Group F with a 100 per cent record after four games although the build-up to the game had been overshadowed by speculation over manager Fabio Capello's future.
For Portugal, tje game was crucial as they lay third behind Russia and Israel with just three wins from six matches.
Postiga's ninth-minute goal proved sufficient to send Paulo Bento's side top, two points ahead of their visitors although Russia - who tonight offered little - have two games in hand.
The teams traded long-range efforts through Joao Moutinho and Viktor Faitzulin before Portugal took a ninth-minute lead through Postiga.
Miguel Veloso's wicked free-kick from the left found the Real Zaragoza striker on the right side of the six-yard box and he slotted a first-time shot in off the post and into the bottom right-hand corner of the goal.
Vieirinha fired wide and Igor Akinfeev was forced to punch Veloso's corner clear as the hosts made their intentions clear.
Their task was aided by two enforced substitutions for Russia, with Viktor Faitzulin and Aleksandr Aniukov both forced off in the first half-hour.
Cristiano Ronaldo shot over the bar from the centre of the penalty area before Russia showed as an attacking force after Portugal's relentless start, with substitute Dennis Glushakov firing wide from the centre of the area.
Ronaldo sent a long-range shot past the right post but Russia were coming more into the game and Roman Shirokov sent an overhead kick over the bar from Dmitri Kombarov's corner.
However, half-time arrived with Portugal ahead and top spot in the group beckoning.
Portugal began the second half on the attack again.
Ronaldo sent a 20-yard shot wide of the left post before forcing Igor Akinfeev into parrying his right-footed effort a minute later.
However, the match went off the boil for a while with neither side showing as an attacking proposition.
Ronaldo appeared to be on his own personal quest and he was the main threat on the field, Akinfeev comfortably gathering another effort from the Real Madrid forward.
Vladimir Bystrov tried an overhead kick in a rare Russian effort on goal but the match appeared to be heading for a narrow Portugal win with Capello's side offering little.
Moutinho fired over from distance and again Ronaldo threatened, Akinfeev repelling his shot from the right of the area.
Ronaldo was hell-bent on scoring, volleying wide deep into injury time, but the hosts had to be content with the one goal.