ParalympicsGB poster girl Ellie Simmonds will bid to be crowned Queen of the pool again on Saturday - but is anxiously waiting to see if she will face her main rival, American Victoria Arlen.
Simmonds, 17, became a national darling of the pool at the Beijing Paralympic Games in 2008, when she won golds in the 100m and 400m freestyle at the tender age of just 13.
However, Simmonds will wait to discover whether her world record-holding rival Victoria Arlen, also 17, will be able to compete in Saturday's S6 400m freestyle.
Earlier this week Arlen was found to be non-eligible by the International Paralympic Committee (IPC) but she immediately appealed.
Arlen, who holds world records for S6 100metres and 400m freestyle, was reassessed and further information provided to the IPC about her disability.
It means Arlen will take part in the heats - but will be reassessed again following the race to see if she needs further re-classification, meaning she may not be allowed to race in the final.
Arlen, a former junior state champion, returned to swimming last year. A neurological virus called transverse myelitis affected her spinal cord in 2006 and left her in a vegetative state for two years.
The IPC said: "This ruling was made because certain information was not provided to the classification panel at that evaluation.
"An athlete who is designated as being NE (non-eligible) usually has an automatic opportunity to protest and be re-evaluated. Because of the unusual circumstances of the evaluation, this opportunity was not available.
"Arlen therefore appealed the NE decision to the board of appeal of classification. The appeal was not contested in order that Arlen could have an opportunity to be re-assessed."