Eleven days of bruising international diplomacy in the French capital appeared to finally open the door to an elusive deal, now expected to be delivered one day after the original Friday evening deadline.
"It will be presented Saturday morning for adoption midday," said a source at the French presidency of the climate talks, an annual gathering that frequently misses deadlines by days.
"Things are moving in the right direction," said Foreign Minister Laurent Fabius, who is presiding over the talks, according to the source who spoke to AFP.
Releasing a fresh draft of the pact on Thursday night that showed progress on some key issues, an increasingly confident Fabius had said a deal was "extremely close".
Fabius instructed the ministers from 195 nations to make unprecedented compromises on the outstanding issues: extremely complex rows primarily pitting rich countries against poor that have derailed previous UN efforts.
World leaders have described the Paris talks as the last chance to avert disastrous climate change: increasingly severe drought, floods and storms, as well as rising seas that engulf islands and populated coastal regions.
The planned accord would seek to revolutionise the world's energy system by cutting back or potentially eliminating the burning of coal, oil and gas, which leads to the release of Earth-warming greenhouse gases.
UN efforts dating back to the 1990s have failed to reach a truly universal pact to contain climate change.
Developing nations have insisted established economic powerhouses must shoulder the lion's share of responsibility as they have emitted most of the greenhouse gases since the Industrial Revolution.
But the United States and other rich nations say emerging giants must also do more, arguing that developing countries now account for most of today's emissions and thus will be largely responsible for future warming.
They are arguments worth hundreds of billions of dollars, which still need to be resolved before the negotiators can leave Paris.