Russia maintain their 100% record at the expense of Portugal's thanks to an early goal by Alexander Kerzhakov.
Alexander Kerzhakov's early goal has helped Russia to a 1-0 win over Group F rivals Portugal at the Luzhniki Stadium.
The result means that Fabio Capello's men have recorded their third win in as many games, taking them three points clear of Portugal at the top of the table.
The Zenit St Petersburg striker dispatched a right-footed effort from inside the penalty area to give the home side the perfect start in the sixth minute.
Helder Postiga and Bruno Alves were both guilty of wasting first-half chances to draw the visitors level.
Paulo Bento brought Silvestre Varela and Antonio Eder on as his side chased the game in the second period, but they could not force an opening.
Portugal are now second in Group F with six points from their three games.
Preview: Russia vs. Portugal >