The Beijing 2008 winners were low-key in edging past Turkey on Saturday night and they were beaten by the United States on Monday.
Their hopes suffered another blow today as they went down to a surprise straight-sets defeat to Republic of Korea.
As is often the case for Jose Roberto Guimares' Brazil side, Sheilla Castro led the way with 16 points, but they were unable to get their block working and ran in to a Republic of Korea side who barely put a foot wrong.
Yeon-koung Kim, their player of the tournament so far, scored 21 points, while Song-Yi Han weighed in with 16 for the Asian side who now look destined for the last eight.
Brazil face China next, who were on the wrong end of a straight-sets defeat of their own against the USA.
The USA moved through to the quarter-finals as they continued their pursuit of what would be a first Olympic gold.
Libero Nicole Davis was brilliant on the floor in defence, while the previously sparsely-used Megan Hodge spiked 18 times off the bench.
Destinee Hooker top-scored for the third time in as many games this tournament with 22 points, while only Zeng Chunlei reached double figures for China.
World champions Russia beat Algeria in quick time to book their place in the quarter-finals.
The Russians were immediately on course for their third win in as many games in Pool A after they raced through the opening set in just 17 minutes before winning 25-7 25-14 25-15.
Russia will next play on Friday against fifth-ranked Japan, who beat the Dominican Republic in today's opening game, while Algeria face a tough ask against second-placed Italy, who saw off Great Britain.
It was better late than never for Turkey as they got their Olympic campaign up and running with a straight-sets win over Serbia.