The 22nd-seeded duo, who had battled through qualifying to reach this stage, posted a 21-14, 21-18 victory in 34 minutes over 11th-seeded Spaniards Elsa Baquerizo and Liliana Fernandez.

They will next face United States duo Lauren Fendrick and Brooke Sweat, with a victory virtually guaranteeing them a position in the knock-out stages.

The American sixth-seeds lost out today 21-17, 21-14 to 2013 world champion Chen Xue, playing with 19-year old partner Xinyi Xia.

Several of Lisboa and Maia's better known compatriots were similarly comfortable today as all seven of the other top eight-seeded teams won as expected.

Agatha Bednarczuk and Barbara Seixas, the top-seeds and reigning world champions, posted a 21-8, 21-15 win in 35 minutes over 32nd-seeded Maria Julia Benet and Virginia Zonta of Argentina.

Talita Antunes and Larissa França, who will join Agatha and Barbara as Brazil’s Olympic beach volleyball entries for the Rio 2016 Summer Games, posted a 21-10, 21-14 win in 31 minutes over Norisbeth Agudo and Olaya Pazo of Venezuela.

The duo won on their last FIVB World Tour appearence at the Rio Open last September on Copacabana Bay.

Olympic qualification is the main aim for both the male and female players competing in the Atlantic resort.

There was disappointment for German veterans Jonathan Erdmann and Kay Matysik, who lost 19-21, 21-15, 17-19 in 56 minutes to Bruno de Paula and Hevaldo Moreira of Brazil.

They then missed out again to Turkey's Murat Giginoglu and Volkan Gogtepe in another three set battle, losing 21-14, 16-21, 15-9 in a match that lasted 50 minutes. 

“It is one of those bumps in the road that every team experiences,” said the 27-year old Erdmann, who is starting his eighth season on the FIVB World Tour with Matysik.

“Give the Brazilians credit, they are in better shape than us right now and they are used to playing in this setting.

"As for the Turkish team, they have been really playing well the past year and are a force to be reckoned with on the tour.”

Pool stage action is due to continue tomorrow with the final round of men's matches and the final two round's of the women's competition.

Knock-out action will then begin ahead of finals on Sunday (February 28).