Helen Clark put in a strong performance in a debate between candidates for the United Nations' top job, but faced strong competition from a newcomer to the race.
The live, televised debate in New York today was the first to be broadcast to an international audience.
An unscientific poll by Al-Jazeera, which hosted the event, ranked Clark and Costa Rican candidate Christiana Figueres as the best performers.
Figueres, who joined the contest last week, previously headed the UN Framework Convention on Climate Change and has been credited with leading efforts towards a meaningful climate agreement.
The debate was split into two parts because of the large number of candidates for the role.
Clark, the only candidate with English as a first language, began by dismissing the idea that the job should go to an Eastern European candidate, in line with the organisation's geographic rotation policy.
Noting that the UN's electoral system lumped New Zealand in with western European countries, she said: "My little country is from the South Pacific and it has never had a secretary-general either.
"I really think when we look at the scale of the challenges the world is facing, we need a global search for the best talent."
She promoted her long leadership experience - "These are issues I have worked on all my life" - and her and ability to make "a lot of hard calls".
Clark did not shy away from the UN's shortcomings, discussing its messy bureaucracy and its patchy record on peace and security.
While not naming any specific event, she said the UN needed to get better at anticipating the warning signs of potential human rights abuses and conflict.
The strongest cheer of the night came when the former New Zealand Prime Minister answered a question on the rise of racism against refugees and immigrants.
"I speak as someone who has seen the acceptance of refugees into my own country," she said.
"And I would say without reservation that those refugees have repaid the hospitality of my country thousands of times over."
To loud applause from the audience, she said: "They are good people looking for a fresh start. That is the approach we must take."
But Figueres nearly stole the spotlight, speaking strongly on a range of issues including the UN's failings in Haiti and sexual abuse by UN peacekeepers in Central Africa.
She was the only one of five candidates to volunteer an apology to Haiti when asked by the debate's hosts.
Clark opted against an apology, saying it was "not wise" to talk about a matter which was being investigated in the courts.
The other candidates in the debate were Bulgarian Irina Bokova, Danilo Turk from Slovenia, and Igor Luksic from Montenegro.
The debate came ahead of the first secret ballot in the UN Security Council on July 21, which will reduce the field of 12 candidates to a shortlist.