Shakhtar Donetsk’s Ismaily will join the squad in the Russian capital as his replacement, the Brazilian Football Confederation (CBF) confirmed at a press conference.
Alex Sandro was himself a replacement after being called into the squad last week after Atletico Madrid’s Filipe Luis suffered a broken leg.
The 28-year-old Ismaily, who was namechecked by coach Tite last month, is now hoping to make his international debut.
The former Olhanense and Braga man, who has made his senior career in Europe, has impressed for Ukrainian side Shakhtar this season, playing a major role in their run to the UEFA Champions League knockout stage which ended against Roma last week.
“I heard that Alex Sandro felt uncomfortable, but I do not know what really happened,” Douglas Costa said.
“For me, the most important thing is to feel the environment of the World Cup, that's what we've all come here to do.”
The only other major absence this month is that of Neymar, who is in Brazil recovering from surgery to a foot injury.
The PSG man’s absence leaves Douglas Costa in line for a rare start under Tite when the Selecao meet World Cup hosts Russia on Friday.
“Neymar is an important part of the team, but now it makes room for others to show what they can do.” Costa continued.
“His absence does not affect us that much. Everyone who has an opportunity will be able to play an important role. These two friendlies will be big tests for us.”