Gold Coast - American Olympic star Missy Franklin reached one final but missed another as she battled a back injury in the opening heats at the Pan Pacific Swimming Championships on Thursday.
The quadruple London Olympic gold medallist and nine-times world champion was fourth fastest in the women's 200 metres freestyle but missed out as only two swimmers per country could make Thursday's final.
Teammate Katie Ledecky was the fastest into the final with 1min 56.45sec ahead of Australia's Melanie Schlanger and American Shannon Vreeland.
Franklin, 19, who suffered back spasms in training on the Gold Coast this week, had to swim again 30 minutes later in the 100m backstroke, where she qualified third fastest for the final behind Australians Emily Seebohm and Belinda Hocking.
Franklin began well in her 200m heat but was overtaken by Schlanger, finishing in 1:57.63.
She again led early in the 100m backstroke but was beaten by Hocking (1:00.46), although Franklin's time of 1:00.60 was enough to make the final.
"I would consider this morning a success. I am really happy that I swam both events but maybe my times were not where I exactly wanted to be but in relative terms I'm really happy with where they are," Franklin said.
"I was able to get out there and race and there was some discomfort but it's getting much better day by day."
Title holder Ryan Lochte was beaten by Australia's Commonwealth Games champion Thomas Fraser-Holmes in his heat of the men's 200m freestyle.
Lochte's fifth-fastest time of 1:47.35 was bettered by teammate Conor Dwyer (1:46.65) in an earlier heat, but Japan's Kosuke Hagino was the fastest qualifier overall in 1:46.60.
The top-ranked Fraser-Holmes was the quickest Australian ahead of team-mate Cameron McEvoy, who won his heat in 1:47.08.
"It was a morning swim and usually my first race is always the worst one so I'm glad that I got that out of the way and hopefully I'll be faster tonight," Lochte said.
American Olympic champion Matt Grevers was fastest ahead of team-mate Ryan Murphy and Japan's Ryosuke Irie into the men's 100m backstroke final. Grevers clocked 52.91sec and was 0.33sec quicker than Murphy.
The strong American team had the top three qualifiers in the women's 200m butterfly with Katie McLaughlin (2:08.02) and Cammile Adams (2:08.22) the favourites for the final.
Japan's Daiya Seto headed Brazil's Leonardo de Deus and teammate Masato Sakai into the men's 200m butterfly final where title holder Michael Phelps was missing after failing to qualify at this month's US trials.
The four-day championships involve the United States, Australia, Canada, Japan and 14 other nations.