"Breakthrough or breakdown by the end of this week." That is the assessment of one veteran Brussels diplomat as Brexit finally really is close to ending its noisy four-year journey of tedium.
But it has suddenly got even more technical.
With just 36 days left, there is absolutely no chance a Brexit deal can be done, then translated into 24 official EU languages, and ratified across 27 member states and in the European Parliament.
None of this is helped by the talks having once more to be conducted by video conference due to Covid-19.
Deals are always better done face-to-face.
Four possible outcomes loom.
1. Crashout calamity.
Still possible as each side plays chicken at the cliff's edge.
The sticking points remain depressingly familiar: a UK guarantee of no under-cutting on state aid rules, labour and environmental laws; agreed EU fishery access to UK waters; and a workable future dispute resolution mechanism.
A crashout is in absolutely nobody's interest.
But five-to-midnight brinksmanship always carries that stark risk.
2. A "skinny" minimalist deal with special provisions to overcome ratification problems.
There are many devices to "politically park" some of the key issues in safety.
The row over state aid rules is one which sticks out.
It's such a complex issue that a high-level working group could take it to the margins and work out a deal anon.
Other rows, like fisheries, can be dialled down by targeted grant aid.
Some kind of "provisional ratification" by EU heads of government could be worked out to avoid a January 1 crashout.
It's already too late for European Parliament ratification at their December 14-18 plenary session.
A special parliament session could be held immediately after Christmas - or it could be pushed into 2021.
Translation of such a huge text takes weeks with linguists, and translators ensconced with lawyers from all nationalities.
Going with an English only text opens the risk of dozens of court challenges.
3. A "stop-the-clock" phoney deadline extension
It's been done before where the EU negotiators just ignored the passing deadline and argued on as though it were interminably elastic.
It cannot be ruled out but we suspect this one is too big for such a device. Extensions have become a row within a row since the UK Leave vote on June 23, 2016. In October 2019 UK PM Boris Johnson childishly undid his public oath against looking for a deadline extension by filing an unsigned letter seeking one.
On July 1 last year he purposely let an opportunity for another negotiation extension, of anything up to two years, just drift by.
4. Late UK capitulation with cosmetic sales help from Brussels.
This element will form a big part of a deal - if there is to be one.
Boris Johnson has an 80-seat majority to push through any deal he deems acceptable.
He is set to make a visible gain in the fishery row which has always been more about political optics than any reality.
The other issues are arcane enough. The UK negotiators are trying to use the lack of time, translation difficulties and other technical devices to put pressure on the EU.
But the Brussels side have spent the last decades doing deals all over the world and know how to pace these negotiations.
They are far more likely to squeeze concessions from London than the other way round.
In a time-worn tradition the EU will help Boris Johnson sell any deal he should make to the British media and people.
That is how the business is done.