Brazil's female gold medal hopes Agatha Bednarczuk and Barbara Seixas recovered from one set down to win 19-21 21-17 15-11 against talented Czech pair who came close to upsetting the home script on the opening day.
Barbora Hermannova and Marketa Slukova appeared to have the momentum midway through the second set but at 10-10 the Brazilians took the lead to drag themselves back into the match.
A thrilling block from Bednarczuk at won them the second set sending the crowd into rapturous applause. In the deciding third set the Brazilians regained control.
"We knew it wouldn't be easy," Bednarczuk told Reuters, explaining that the excitement of playing in front of a home crowd on Rio's famous beach had maybe caused them to lose a little focus.
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After the first set "we were able to calm down a bit and put more tactics into play," she said.
Earlier on Saturday, Alison Cerutti and Bruno Schmidt beat Canada's Josh Binstock and Samuel Schachter 21-19 22-20 to seal their credentials as gold medal favourites in the men's tournament.
"It was incredible," Cerutti told Reuters, still beaming after the performance.
With beach volleyball one of Brazil's favourite sports, particularly in Rio where nets dot the coastline, the local athletes were fired up by an enthusiastic crowd waving green-and-yellow flags, many wearing swimsuits.
"To start an Olympics at home, to see this crowd shouting Brazil, it's a dream come true," added Cerutti.
Brazil's men's pair were not given an easy ride and fell behind in the second set, but scrambled back to make it 20-20.
The next point proved to be vital with the Canadians left to rue a crucial challenge that did not go their way after Binstock fouled at the net. The visiting pair said the hostile crowd, which booed at times, had made things difficult.
One point later the match was over and the crowd erupted as the Brazilian winners signed the ball and launched it into the crowd.
The Brazilian men will now prepare to play Austria while the women face Argentina on Monday.
"The focus is to play and win... Gold comes as a result of that," said Cerutti.
(Reporting by Stephen Eisenhammer; Editing by Ken Ferris)
