Freestyler Lauren Boyle looms as an outside medal chance in the 800m freestyle after qualifying fifth fastest for the London Olympic final.
Boyle (24), who contested the 400m final earlier in the week, swam a sensible race to finish second in Heat Five, four seconds behind fastest qualifier Rebecca Adlington of Great Britain.
Her time of 8m 25.91s shaved 0.39s off her national record, set when she won the World University Games title in China last year.
The women's 800m freestyle final is scheduled for 6.45am Saturday (NZT).
But Daniel Bell was well off the pace in the men's 100 butterfly heats, clocking the 37th-fastest time of 53.76s and failing to progress to the semifinals. Bell led through the first 50m of his race, but faded down the final length to finish fifth.
South African Chad le Clos was the fastest through to the next round with 51.54s, but American Michael Phelps showed he could add to his medal collection, pacing himself through to victory (51.72s) over Crotian archrival Milorad Cavic in the final heat. Phelps was dead last at the turn, but came storming home to pip the man he beat for the gold medal at Beijing four years ago and clock the second-fastest time of the day.