In his place on the virtual retreat was Chinese Foreign Minister Wang Yi.
Officials later confirmed that was indeed the case.
Having Biden and Xi at the same table had placed huge expectations of Ardern's chairmanship; her foreign minister had after all earlier suggested New Zealand could act as a peace broker between the United States and China during NZ's year as Apec host.
But more than that, given the geopolitical tensions between the two great powers, it had been seen as a personal triumph for Ardern that both presidents had agreed to attend together virtually.
The problem for Ardern's stewardship of Apec is that while the informal retreat proved a much-needed vehicle for avoiding what the PM calls "vaccine nationalism" and instead forged a collaborative approach to tackling the Covid-19 pandemic, the geopolitical tensions did still colour the event.
Xi's video statement (the text was released in full on Xinhua net) emphasised the "Asia-Pacific is a major engine for global economic growth".
The Chinese president stuck to the Apec script, emphasising for the member economies defeating Covid-19 and restoring growth at an early date are "our top priority" for the time being.
Said Xi: "Since the start of the pandemic, Apec members have united as one and carried out active co-operation against the coronavirus. Being the first to gain the momentum for recovery, the Asia-Pacific economy has made contributions to driving the world economy.
"Last year, we adopted the APEC Putrajaya Vision 2040 and set ourselves the goal of an open, dynamic, resilient and peaceful Asia-Pacific community, charting the course for economic co-operation in the Asia-Pacific."
There was more besides: particularly a desire by Xi to forge a Free Trade Area of the Asia Pacific (FTAAP) which has long been an Apec goal.
Both Both Xi and Biden emphasised their respective countries' contribution to regional vaccine rollouts. (China announced a US$3 billion fund).
But Biden went way beyond the Apec script, using the event to reiterate his commitment to a free and open Indo-Pacific" saying he hoped the region would adopt a "values-based" and "transparent" vision.
Last week, Ardern embraced the Indo-Pacific concept in an address to the Institute of International Affairs "Standing in the Future" conference.
Unlike Apec which has a secretariat and an enormous work programme stretching back more than 30 years, the "Indo Pacific" is still essentially a political construct.
There is no formal secretariat. New Zealand is at this stage a bit player in that dance.
But Apec matters to New Zealand. That's where policy consensus is forged on many economic issues of importance to New Zealand. It is one of the few clubs in which New Zealand plays an influential role.
Ardern doesn't need Biden to rain on her parade.
A subtle nudge to tone down his "Indo-Pacific" rhetoric by the time the 21 Apec – that's Asia-Pacific – leaders reconvene under her chairmanship for their formal November leaders' meeting - would not go astray.
It will be a test of her leadership to do so.
