Japan lead Brazil 1-0 at the interval of their Olympic quarter-final clash.
It was the Brazilians who started the better, with Cristiane coming close to opening the scoring after just two minutes.
Francielle had an effort of her own moments later, but her free kick was saved by Miho Fukumoto in an impressive opening spell.
Brazil continued to dominate as they forced a series of early corners, while Marta brought the best out of Fukumoto with 13 minutes on the clock.
Brazil's best chance fell to Renata Costa after 17 minutes, but she fired it high and wide from inside the penalty area.
The chances continued to fall for Brazil, and but for another smart save from Fukumoto, Jorge Barcellos's side would have taken the lead courtesy of Marta.
For all Brazil's pressure, the best chance of the half fell to Japan after 25 minutes, but Shinobu Ohno fired wide when Yuki Ogimi was unmarked inside the box.
Japan did eventually force the opening goal in their best spell of the match, however, when Ogimi slotted past Andreia after 27 minutes.
Brazil gained back a period of control in the final 15 minutes of the half, but they entered the break behind.
