The Black Caps are confident captain Kane Williamson and Henry Nicholls will recover from illness and be available for the third and final cricket test in Australia.
Just two days out from the match in Sydney, Williamson and fellow top-order batsman Henry Nicholls both missed Wednesday's training session with flu-like symptoms.
But bowling coach Shane Jurgensen said the two players are fine and should be back training on Thursday.
The news came with the Black Caps already 2-0 down in the series after comprehensive defeats in the first two matches in Perth and Melbourne.
A potential absence for Williamson or Nicholls for the game starting at the Sydney Cricket Ground (SCG) on Friday would be compounded by a lack of batting cover in the touring squad.
Opener Jeet Raval, who was dropped for the second Test after his poor run of form continued in the first match, was the only batsman in the group who didn't play at the MCG.
Despite scoring only 57 runs in four innings across the first two Tests, the loss of Williamson would be a big blow to a batting line-up who were bowled out for less than 200 in three of those four innings.
The Black Caps skipper is regarded as one of the sport's premier batsmen, with 21 Test centuries to his name and a stellar Test average of 51.44.
No 5 batsman Nicholls has also struggled in the first two Tests, yielding just 61 runs from his four innings, but his five Test tons and average of more than 40 indicates he would also be a significant loss.
Meanwhile spin bowler Will Somerville has joined the New Zealand squad in Sydney.
Called up as a replacement for injured seamer Trent Boult, Somerville has taken 14 wickets in his three Tests.
The 35-year-old spent time playing in Sydney before his return to New Zealand, turning out for New South Wales 12 times in first-class cricket and taking 23 wickets in five appearances at the SCG.