Overall, though, this was a game that did not quite match the standards of drama and excitement set during the Germans' 5-5 draw with China PR and Canada's comeback win over Finland earlier in the day. Nonetheless, it was keenly contested throughout and, amid some ferocious tackling, Brazil enjoyed the better of the first half, dominating possession and forcing the best of what little chances there were.
The best opportunity of the opening period came after 15 minutes, when Carol leapt highest at a corner only to see her goal-bound header hacked off the line by USA No2 Christina Gibbons. But the change in tone after half-time was evident within seconds of the restart, with Margaret Purce - one of Americans' brighter players - attempting a cross-shot that beat keeper Leticia only to bounce to safety off the underside of the crossbar.
Michelle French's side continued to press though and with 52 minutes gone they saw a glorious chance go begging. Mackenzy Doniak did well on the right before delivering an inch-perfect cross, but substitute Taylor Racciopi - unmarked, six yards from goal - directed her header over when it seemed easier to score.
Brazil were struggling to cope with USA's power and pace, and with 68 minutes Rose Lavelle burst purposefully beyond the South Americans' defense. But although Leticia could only parry clear, the rebound arrived too quickly to Horan and bounced off the striker's midriff and behind for a goal kick.
The US pride themselves on tenacity, though, and there was plenty of that on display in the goal that won the match with eight minutes left to play. Horan claimed it, side-footing confidently home from 12 yards, but it was Summer Green who deserved the bulk of the plaudits, having scrapped for possession on the right before picking out her team-mate with a measured, unselfish cutback.
The Americans will now go on to face China PR in a match decisive to both sides' chances, while Brazil need to beat Germany if they are to stand any chance of making it through.