Why US rematch in 4x100 at Rio Olympics

In the women's 4x100-meter relay preliminaries, the U.S. team made a major error in the handoff between the 2nd and 3rd batons and did not finish in the final. The U.S. team appealed after the preliminaries, stating that the dropped baton was due to interference from the Brazilian team beside them. After reviewing the video, the Arbitration Committee ruled that the Brazilian team's score should be canceled, and the U.S. team's appeal was successful and they were awarded a separate rematch. The final result was that the U.S. team ran 41:77 in the individual rematch, squeezing past China into the final.