NBC Olympics.com – Sweden's Sarah Sjostrom, the reigning world champion, set the Olympic record in the 100m butterfly in Saturday's but missed her own world record by about two-tenths of a second. Sjostrom clocked 55.84 to advance to Sunday's final in first place.
Team USA's Dana Vollmer, the 2012 Olympic champion in the event, qualified in fourth place with 57.06 seconds.
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Fellow American Kelsi Worrell missed the final, finishing in ninth place by 0.03 seconds.
Earlier in Saturday's preliminary heats, Vollmer went a best time since she gave birth to her son Arlen, which she did in March 2015.