Title favourite Russia routed Britain 37-16 in the host's second drubbing of the tournament after its 31-19 defeat in Saturday's opener against Montenegro.
Brazil shared top spot with Russia after winning a tight battle against Montenegro 27-25.
Earlier, Croatia got its first win by defeating Angola 28-23, leaving the African team with no points.
Left winger Jo Hyobi scored five times to help South Korea edge Denmark 25-24 and send her team top of the table in Group B.
In a match between two multiple Olympic champions, South Korea led 24-19 with four minutes left when left back Pernille Larsen reeled off four goals which nearly earned Denmark a draw.
Defending Olympic champion Norway recovered from its opening loss to France by defeating Sweden 24-21. Sweden is the only team in the group to lose both its matches.
In the remaining Group B match, former world champion France and Spain drew 18-18.
The top four teams of both groups advance to the quarterfinals.