Boris Johnson’s Brexit deal is expected to pass easily through Parliament on Friday – as he uses his commanding majority to push through leaving the EU from day one.
That would mean Britain leaving the bloc on January 31, as Mr Johnson planned.
The country will then begin a transition period in which EU rules will still apply here.
But the PM has also promised Britain will have a free trade deal with Brussels by the end of 2020, which makes for a tight timetable.
And the EU’s chief Brexit negotiator Michel Barnier is warning that negotiations cannot be completed in such short a time.
So whatever Boris does this week, next Christmas Britain could be facing a potentially disastrous no-deal all over again.

The Queen’s Speech on Thursday will make Mr Johnson’s promised £34billion a year to be pumped into the health service by 2023-2024 legally binding for the first time.
Mr Johnson’s new government programme will also stop local authorities boycotting goods from Israel on political grounds.
And he will fulfil his promise to end early release for jailed terrorists. Meanwhile, Mr Johnson started a tour of former Labour strongholds in the North of England yesterday and pledged to repay their trust for helping to deliver a huge Conservative majority.
The election saw the crumbling of Labour’s Red Wall of formerly safe seats in mainly working class areas across the North and central England.

Mr Johnson met supporters in Sedgefield, Co Durham, which was once held by former Prime Minister Tony Blair , Labour’s most successful leader. He told them: “I know that people may have been breaking the voting habits of generations to vote for us.
“I want the people in the North East to know I will repay your trust. We are not the masters. We are the servants now.”
Labour had held Sedgefield since 1935. In 2005, Mr Blair’s majority there was 18,449. On Thursday, Tory Paul Howell took the seat from Labour’s Phil Wilson by more than 4,500 votes. But Sedgefield was just one of seven Northern constituencies captured from Labour on Thursday.
Tomorrow Mr Johnson will replace Cabinet ministers Nicky Morgan at Culture and Alun Cairns as Welsh Secretary.
Mr Cairns quit during the campaign. Mrs Morgan decided not to not contest her Loughborough seat on Thursday.
The PM has pencilled in a wide-ranging Cabinet reshuffle in February to coincide with a shake-up of Whitehall departments.
This could see the Department for International Development merged with the Foreign Office.

MPs will return to Westminster on Tuesday to be sworn in before the State Opening of Parliament on Thursday.
On Friday night, Mr Johnson and girlfriend Carrie Symonds joined Mick Jagger at media magnate Evgeny Lebedev’s Christmas party in London.
Tory former Prime Minister David Cameron and his wife Samantha were also there, along with Princesses Eugenie and Beatrice, actors David Walliams , Anna Friel and David Hasselhoff, plus Rod Stewart’s wife Penny Lancaster.