Ziegler touched in 2 minutes, 1.72 seconds for her second victory in two days. The 2008 Olympian won the 400 free on Friday and will swim the 800 free Sunday against her former idol, Janet Evans, who at 40 is attempting a comeback for the London Games.
Gandy, a 20-year-old Brit who trains in Australia, won the 100 fly in 58.90 in her first American competition. Lyndsay De Paul was second at 1:00.01.
Aussie Joshua Beaver won the 200 backstroke in 1:59.31 ahead of countryman Matson Lawson, who made Australia's Olympic team.