Two sides finished with five wins from five - Russia in Group A and the United States in Group B.
Russia won the race to finish top of the pile, coming out on top 3-2 in a straight shoot-out with Italy this afternoon.
The world champions and their Italian rivals were neck and neck heading in to the clash and Russia twice came from behind to get over the line.
The USA, meanwhile, eased to a 3-0 win over Turkey to sign off their group stage campaign.
Russia will face defending champions Brazil - last-gasp qualifiers in Group B following a 3-0 win over Serbia in the day's late game - while the Dominican Republic lie in wait for the USA.
The Dominicans needed just 69 minutes to brush past Algeria to put themselves in the quarter-finals at the expense of Great Britain today.
China and Japan meet in an all-Asian affair after they beat Republic of Korea and Great Britain respectively today, while Italy will go up against Republic of Korea in the fourth and final encounter.
The quarter-finals take place on Tuesday.
My Olympics
Follow your favourite countries and sports