New Zealand skipper Kane Williamson and his team mate Henry Nicholls were sent back to the team hotel with "flu symptoms" on Wednesday, but the team are confident they will be fit to face Australia in the third test on Friday.
The batsmen turned up at the Sydney Cricket Ground for an optional training session but team medical staff thought it best to keep them away from the other players so they were given the day off.
"They're fine, they're not really feeling good today," bowling coach Shane Jurgensen told reporters.
"They had some flu symptoms and I'm sure they will be back training tomorrow. They're pretty tough, so just take a rest today. It's been a big last two tests so it's a good opportunity to have a day off and come back tomorrow."
While Australia have already sewn up the three-match series with victories in Perth and Melbourne, victory at the SCG would elevate New Zealand from fifth to third place in the World Test Championship table.