The Barcelona striker was ineffective during much of Brazil's last-16 win over Chile after he suffered early knocks on the right knee and left thigh. (Agencies)
However, although he left the field for treatment, he played on and scored Brazil's final penalty in the 3-2 shootout win after the match ended 1-1 after extra time.
Manager Luiz Felipe Scolari said the injuries were the reason for his unusually quiet showing and the 22-year old will be allowed to miss training if necessary.
Scolari spared most of the first team from training on Monday, preferring to have them do light gym work at the squad's base in Teresopolis, around 100 kilometres from Rio de Janeiro.
Goalkeeper Julio Cesar, who was the hero of the win after saving two Chilean penalties, was the only first-choice player to train, alongside fellow keepers Victor and Jefferson.
Runco said defender David Luiz, who passed a late fitness test on a sore back before the Chile game, had "recovered well" and was practically 100 percent fit again.
The team's only other injury concern is Luiz Gustavo, who Runco said is complaining of a sore knee.
However, the midfielder will miss the next game after picking up two yellow cards and so has time to recover.
The Barcelona striker was ineffective during much of Brazil's last-16 win over Chile after he suffered early knocks on the right knee and left thigh.