The 18-year-old Olympic gold medalist won her second straight national title on Sunday, rallying from fourth during the final day of competition with four poised and professional routines. Rivera was the self-described “underdog” in Paris two years ago, when she joined an experienced group that helped the Americans win their third team gold in four Games. While some of her Olympic teammates — Biles and Suni Lee chief among them — have been on an extended break (though Lee announced last month she has started training for a return to competition), Rivera has pressed on. The judges awarded Rivera with a solid if not spectacular 13.850, and her momentum continued to build as she made her way across the competition floor at Matchup Mortgage Arena. Two-time Olympic gold medalist Jade Carey, who is methodically building difficulty into her routines as she eyes a third trip to the Games, finished fifth in a meet that doubled as a homecoming for the Phoenix native.