Mr Pena Nieto took over from Felipe Calderon, who had been President since 2006 and whom Mr Key said he knew fairly well.
"By virtue of alphabetical fate, Mexico always sits next to New Zealand at Apec, so I spent quite a lot of time talking to Calderon."
Mr Pena Nieto has so far focused on pushing through his reform agenda, including education changes and his promised National Gendarmerie of 40,000 to tackle drug crime.
But Mr Key will be seeking confirmation that the new President will keep to the promise made by his predecessor to support New Zealand's bid for a Security Council seat in 2015-16 over Spain and Turkey.
Part of his message is likely to include a subtle reminder that New Zealand backed Mexico's bids for a seat in 2002 and again in 2009, as well as its candidate's bid to be Secretary General of the OECD in 2005.
Mexico naturally looks predominantly to its north - to the United States - in its international relations.
However, in one of his first moves as President, Mr Pena Nieto made promising noises about free trade and the Asia Pacific.
In an opinion piece for the New York Times soon after the election last July, Mr Pena Nieto spoke about trade with the United States, and added: "I similarly intend to start a new era of economic and political co-operation with the Asia-Pacific region."
Mexico was one of the most recent countries to join TPP negotiations, signing up in 2012. New Zealand has been trying to start free trade talks with Mexico since 2004 - but that is now more likely to be done through the TPP agreement.
Mr Pena Nieto's campaign also advocated energy reforms, such as opening up the state-owned oil company Pemex to competition.
That's a topic that will also give the two leaders something in common, as Mr Key sets about partial asset sales.
Mr Pena Nieto could have a harder time of it because state ownership of natural resources is written into Mexico's Constitution.
Mexico
*Population: 115 million.
*NZ's 27th largest trading market.
*NZ exports to Mexico: $281.7 million in 2012, mostly dairy.
*NZ imports from Mexico: $252.8 million (machinery, electronic devices such as flat-screen televisions and Blackberry mobile devices.)
*GDP: US$1194 billion, 2nd largest economy in Latin America.
*NZ companies investing in Mexico include Fisher & Paykel Heathcare, Fisher & Paykel Appliances, and Pumpkin Patch, which has opened stores in Mexico.
*Last year, 3152 people from Mexico came to New Zealand, including 2120 on short-term stays such as a holiday and 203 for more than a year.