Former Prime Minister Helen Clark faces a grilling from the United Nations General Assembly overnight as she bids for the top job.
The head of the UN Development Programme wants to be the first female Secretary-General when Ban Ki-moon steps down at the end of the year.
She faces strong competition from UNESCO head Irina Bokova from Bulgaria, who was quizzed two nights ago.
The UN custom of rotating between regions is expected to favour a candidate from Eastern Europe.
Former Australian Prime Minister Kevin Rudd is also mulling running for the job.