New Zealand cricket captain Stephen Fleming is struggling with a mystery virus which has thrown his preparation for next week's first test against Australia into disarray.

What first appeared as a routine viral ailment has completely floored Fleming and is threatening to play havoc with his involvement in the two-Test series, which starts in Brisbane Thursday week.

Fleming delayed his departure to Sydney, meaning he will miss the lead-up game, a four-day match against New South Wales.

"I just can't stay awake, I'm sleeping all the time," Fleming told The Dominion Post.

"Malaria's been ruled out, but I'm not feeling that flash at the moment and I'm just really lacking energy."

When asked about his Test prospects, Fleming said: "I need some improvement. It's still a week or so away, so hopefully ..."

Fleming visited a Wellington doctor on Tuesday and it is hoped blood tests will shed light on the untimely complaint.

It is possible that Fleming picked up something on the recent tour of Bangladesh.

"When I got back I started to feel fatigue-like symptoms and ever since I've slowly gone downhill."

Fleming has rearranged his flight to Sydney for Friday and said the other reason for his delay was to keep his distance from his team-mates.

Brought to you by AAP © 2024 AAP