Brazil's Adriana Behar and Shelda Bede booked their place in the last 16 with victory over Cuba despite complaining of burning sand underfoot.
The Brazilian duo beat Cuba's Tamara Larrea Peraza and Dalixia Fernandez Grasset 21-14 21-19 to retain their unbeaten run in Group B.
"The sand was so hot," said Behar. "I asked them to water it but they said they couldn't."
Players can ask for the sand to be watered but the referee can veto it.
In the men's event, Switzerland's Paul and Martin Laciga also struggled against the searing temperatures.
The brothers started the match sluggishly but recovered to beat Austria's Nikolas Berger and Florian Gosch 21-17 21-19 to reach the next round.
"In this heat you cannot just go 100 percent the whole
time, which is hard for me," said Martin.
Other Group C action saw Spain top the standings after a shaky 21-16 19-21 15-11 win over Austria's Robert Nowotny and Peter Gartmayer.
The two top teams and four best third-place teams move on to the single-elimination round of 16 which begins on Friday.