Brazil coach Tite rued not giving Vinicius Junior his international debut in Friday's friendly against Colombia, owing the decision to Neymar displaying "perfect" body language upon his return.
Real Madrid talent Vinicius has long been tipped to make the breakthrough at senior level for Brazil, having sparkled in his fledgling career with Flamengo and then last season in Spain.
Injury denied him a first cap in March after he was called up for matches against Panama and Czech Republic, while he failed to make the cut for Tite's Copa America squad.
Tite planned to let the 19-year-old feature as Brazil drew 2-2 with Carlos Queiroz's Colombia, but instead opted to keep Neymar – playing his first match for club or country in three months – on the pitch in an attempt to maximise the Paris Saint-Germain star's fitness.
"Vinicius was ready to enter," Tite told reporters. "The idea was to for him to come on, but circumstances change.
"He will have his chance. Of course, he will be used as a left winger. Playing in the national team is already complicated, the yellow shirt weighs on anyone.
"So, in the case of Vinicius, I will put him in his natural position, where he is accustomed and feels comfortable.
"The plan was not that Neymar played 90 minutes, he came from more than three months without playing, and I was about to take him off three times during the second half, but he was improving technically and physically as the minutes passed.
"I was talking with Dr. Rodrigo Lasmar and our physio during the match and we decided to leave him on the pitch.
"I don't think he expected me to play him for 90 minutes, I saw him look at the bench a couple of times, but his body language was perfect, he was not tired and there was no point in taking him out.
"The level of the game was so high and I saw the team at such a good pace that I didn't want to make any more changes."
Neymar scored Brazil's second goal, after a Luis Muriel brace had cancelled out Casemiro's headed opener.
Brazil are next in action against Peru on Wednesday.