The forward helped Brazil to World Cup qualifying wins over Ecuador and Colombia, netting once in both games.
Neymar landed in Spain on Wednesday, just days out from Barca's encounter at home to Alaves.
Despite fatigue, the 24-year-old said he was confident of featuring for his club for the first time this season, having also led his nation to Olympic gold in Rio.
"Very glad to be home. Do I look like playing on Saturday? Sure," Neymar said.
He added: "I'm a little tired now. I need to rest and then resume training with team-mates."