Theresa May was given a fresh warning about the difficulties she will face in Brexit negotiations with Europe as peers prepared for battle with ministers over the Article 50 Bill.
The Prime Minister was warned by the Czech EU minister that unless British negotiators were prepared to compromise in talks with the European Union the negotiations could result in a "crash landing".
Before talks begin, the legislation allowing Mrs May to trigger Article 50 needs to clear Parliament, where the House of Lords will begin a marathon debate on Monday amid warnings peers are ready to rewrite the Bill.
Around 190 peers are expected to speak during the two days set aside for the European Union (Notification Of Withdrawal) Bill's second reading debate in the Lords, the first time the upper chamber will debate the legislation.
Labour and Liberal Democrat peers have indicated they are ready for battle, with efforts likely to focus on guarantees for EU citizens' rights and the ability of Parliament to have a meaningful vote on the final Brexit deal.
Votes are not likely at this stage, with efforts to force through amendments likely to come later in the Bill's passage through the Lords.
Once the two-year countdown to Brexit begins after the triggering of Article 50, which Mrs May has vowed to do by the end of March, the negotiations with the EU can commence, but the Prime Minister has been warned they will not be straightforward.
Czech minister Tomas Prouza told The Guardian: "There is a real danger that British politics, with all its whipped-up resentments of Europe, will mean British negotiators are unable to compromise, and we will head for a crash landing."
Senior German MEP Elmar Brok, an ally of Angela Merkel, told the newspaper: "The British government tries to divide and rule. They believe they can take members of parliament out of certain nations ... to win support by dividing us.
"If they try to negotiate while trying to interfere in our side then we can do that too. We can make a big fuss over Scotland. Or Northern Ireland."
The Financial Times reported talks on a future trade deal with the EU could not begin until after Christmas because Brussels officials led by Michel Barnier want to make progress on the process of separation first.
That will include talks on an exit fee, expected to be up to 60 billion euro (£51 billion), and the rights of expatriate citizens, something Mrs May is also keen for early progress on.
A senior eurozone official who had been in contact with Mr Barnier told the newspaper: "He thinks we will be discussing money and acquired rights until December ... No trade, nothing about the future, just the past."
The UK wants to discuss trade talks in parallel with the so-called divorce settlement, and hopes to wrap both elements up within the two-year time deadline after triggering Article 50.
In the Lords, former European commissioner Lord Mandelson has urged his colleagues not to "throw in the towel early" in the fight with the Government.
The Labour peer insisted there is a "strong body of opinion" among peers over guaranteeing the future of EU nationals living in the UK and in giving Parliament a vote on the final Brexit deal in which the Government could be sent back to negotiate a better arrangement.
Lord Newby, the Lib Dem leader in the upper chamber, also pressed for amendments to give EU nationals in Britain the right to stay.
"The Government is generating real fear and uncertainty amongst large numbers of people," he said.
"Every day we are hearing passionate pleas from people whose partners, friends and colleagues are living with a shadow of doubt hanging over their future in the UK.
"This is no way to treat people who have settled in our country and contributed hugely to our economy and society.
"We want to give Theresa May the chance to think again and grant EU nationals in the UK the right to remain now."