Lauren Boyle could withdraw from NewZealand's 4x200m freestyle relay team.
In the wake of the Olympic 400m freestyle final, where she finished eighth in a slower time than her heat, Boyle is scheduled to return to the pool in the women's relay heats on Wednesday evening.
It's a team which claimed silver at the 2010 Commonwealth Games in Delhi and would have a good chance of qualifying for the final.
But that would also mean Boyle facing potentially two more races before her individual 800m freestyle heat on Thursday night.
As with the 400m, Boyle has a chance of qualifying for the Olympic final, but swimming two 800m races and two 200m races in the space of 36 hours would seriously compromise her individual performance.
If Boyle were to withdraw, New Zealand could still field a team in Penelope Marshall, Samantha Lucie-Smith, Natasha Hind and Melissa Ingram.
A decision is expected over the next two days.
- Fairfax Media