Preparations by multiple Olympic and world champion Missy Franklin for this week's Pan Pacific Championships have been hit by back trouble but she was on the mend, US team officials said on Wednesday.
The 19-year-old suffered back spasms in training and was undergoing treatment before her scheduled opening swims at the meet on Australia's Gold Coast on Thursday.
But the quadruple London Olympic gold medallist and nine-time world champion said she was feeling "drastically better" late Wednesday.
"First of all, I have to thank our medical team for their amazing work and also my teammates, coaches, staff and fans for all their heartfelt support," Franklin said in a USA Swimming statement.
"I am feeling drastically better every hour that goes by and hoping and praying that I will be ready to race tomorrow.
"We will consistently coordinate with team doctors and staff to make the best decisions for myself and my team."
Franklin swam in a local pool Wednesday where she tested her back with minimal discomfort.
"It was very therapeutic and felt great being back in the water," Franklin said.
USA Swimming said Franklin's status for the scheduled 200-metres freestyle and 100-metres backstroke would be determined before preliminary heats on Thursday's opening day of the four-day meet.
She has also qualified for the 200m backstroke and 100m freestyle and could contest the three relays.
Franklin is the current Laureus sportswoman of the year, having beaten tennis great Serena Williams and Russian pole vault queen Yelena Isinbayeva for the global honour.