Ariarne Titmus said Saturday she can't believe "a goofy girl" from Australia could win back-to-back Olympic 400-meter freestyle titles, while lavishing praise on rival Katie Ledecky.

The down-to-earth 23-year-old held off Canadian teenager Summer McIntosh and American great Ledecky to join Dawn Fraser as the only Australian female swimmer to retain an Olympic crown.

The world record holder was in full control to touch in 3 minutes, 57.49 seconds ahead of McIntosh (3:58.37) and Ledecky (4:00.86), who faded badly in the final 50m.