The 34-year-old, Brazil's all-time leading scorer, was named in the squad on Monday, marking his return after a prolonged injury layoff that kept him out for much of the qualifying campaign, as Brazil chase a record-extending sixth title.
Much of the build-up to the squad announcement centred on coach Carlo Ancelotti's decision over whether to include Neymar.
The Italian, who took charge of Brazil last year, had not previously recalled the former Barcelona and Paris St Germain attacker, who now plays for Santos and is set to feature at his fourth World Cup in pursuit of his first world title.
"Neymar has a minor calf injury, an oedema," Santos' head of medical services Rodrigo Zogaib told Brazil's ge.globo on Wednesday. "But, according to our planning, his progress will allow him to be fit next week when he will join up with the national team."
Neymar, who has 79 goals in 128 internationals and has not featured for Brazil since 2023, continues to face scrutiny over his fitness and form.
His stint at Saudi club Al Hilal was disrupted by injuries, and he returned to boyhood club Santos last year but has struggled to recapture his form.
Neymar missed Santos' 2-2 home draw with San Lorenzo in the Copa Sudamericana on Wednesday.
Brazil open their World Cup campaign against Morocco on June 13th in New Jersey, before facing Haiti and Scotland in Group C.
They are scheduled to play warm-up matches against Panama on May 31st and Egypt in the lead-up to the tournament.