The Brazilian Football Federation confirmed on Wednesday that Fluminense midfielder Martinelli will replace him, although it did not disclose the nature of Pedro’s injury.
The 24-year-old had been recalled after his surprise omission from Carlo Ancelotti’s World Cup squad, according to ESPN.
He has made an impressive start to the season, scoring three goals in six appearances and winning the Premier League Player of the Month award for August.
Chelsea are yet to comment on his condition, with Pedro having played the full 2-2 draw against Hull last weekend, scoring in the process.
The Blues face Brentford on Friday before the international break, while Brazil will play Australia and India later this month.
