Spain stay perfect in Olympics Group C, Marta leaves field in tears
The Brazil great narrowly missed Olga Carmona's head with an out-of-control attempt to reach the ball in first-half stoppage time, receiving a straight red card in what could turn out to be her final-ever Olympic game.
Brazil needed a win to secure a place in the knockout rounds, but now they face a nervous wait to see if they will be one of the two best third-place teams in the last eight – a match they would have to play without their captain.
Athenea del Castillo eventually got the breakthrough after 68 minutes, before Alexia Putellas scored in the 107th minute to ensure they stayed perfect to top the group.
It was a dominant performance by La Roja, who created an expected goals tally of 2.75 from 27 shots compared to Brazil's 0.3 from 10 efforts.
Spain will face the best third-place team from either Group A or B in the quarter-final on Saturday.
Meanwhile, Japan also secured a spot in the knockout rounds with an emphatic 3-1 victory over Nigeria.
Japan stunned Brazil in the second group game and continued their momentum by getting the job done in the first half.
Maika Hamano and Mina Tanaka put them 2-0 up before Jennifer Echegini pulled one back for Nigeria.
However, Hikaru Kitagawa's strike just before the break restored Japan's two-goal cushion and held onto that lead to set up a meeting with the winners of Group B in the next round.