The two stars, of Beijing Guoan and Gremio respectively, come into the squad to replace the injured Douglas Costa, of Bayern Munich, and Shakhtar Donetsk's Fred
Renato Augusto and Walace will join the Brazil squad at August’s Olympic Games in Rio.
The midfield duo were included in the Selecao’s final 18-man squad which was submitted to the International Olympic Committee on Thursday as the two changes to the original squad released earlier this month.
Beijing Guoan’s Renato Augusto replaces Bayern Munich’s Douglas Costa who withdrew through injury, while Gremio’s Walace comes in for Fred after Shakhtar Donetsk refused to sanction his release.
Paris Saint-Germain defender Marquinhos has also been confirmed in the squad, despite the French champions writing to the Brazilian Football Federation (CBF) earlier this month to announce they do not plan to release him for the games.
Felipe Anderson’s place was also thought to be in doubt, but his presence was confirmed after the player thanked Lazio for agreeing to allow him to participate.
The final squad list also features four alternates, though their names were not made public.
Coach Rogerio Micale is now hoping no other clubs will step forward to block the participation of any of his players.
The under-23 tournament is restricted to players born on or before January 1, 1993, though each club is permitted three overage players.
28-year-old Renato Augusto joined 37-year-old Palmeiras goalkeeper Fernando Prass as one of those wildcard slots.
The third overage-player position was filled by senior team captain Neymar, who skipped last month’s Copa America in order to lead Brazil in their quest for the country’s first ever Olympic gold medal in football.