The Americans (5-0) recorded their fourth shutout in five games and needed just five innings Saturday to beat Taiwan (1-4), which hasn't defeated the U.S. in a major competition since 1982.
Mendoza's homer leading off the third ignited a five-run outburst for the U.S. team, which has outscored its opponents 36-1 so far and allowed just four hits in 29 innings.
Lovieanne Jung and Lauren Lappin added two RBIs apiece for the Americans, who are seeking their fourth consecutive gold medal in softball's final appearance in the games until at least 2016.