Brussels must be “more flexible” in Brexit talks, David Davis will demand this week as he seeks to bounce the European Union into concessions during face-to-face talks.
The Brexit Secretary is expected to tell EU negotiators they must prove the legal basis for their vast divorce bill proposal and agree to less influence for European judges.
Mr Davis is set to tell Michel Barnier, the European Commission's chief negotiator, that the Commission should not "drag its feet" when they meet again in Brussels.
It comes after tensions between both sides triggered a briefing war, with EU figures accusing the UK of using Northern Irish peace as a Brexit “bargaining chip”.
The pair will first meet on Monday - with Mr Davis ignoring the British bank holiday - before holding more substantive talks at the end of the week. Officials will be negotiating throughout.
Talks will focus on the technical detail of how Brexit will work after a string of policy papers were published by the UK over the last fortnight.
Britain wants to talk about a future trade deal from October, but the EU is yet to decided whether “sufficient progress” has been made on separation issues such as EU citizens rights.
A Government source said: “The UK has been working diligently to inform the negotiations in the past weeks, and has published papers making clear our position on a wide range of issues from how we protect the safe flow of personal data, to the circumstances around Ireland and Northern Ireland.
“Now, both sides must be flexible and willing to compromise when it comes to solving areas where we disagree.
“As the EU itself has said, the clock is ticking so neither side should drag its feet."
An official agenda published on Friday sets out how this week's negotiations will include the rights of EU citizens rights, Northern Ireland, and the question of a divorce settlement.
But Mr Davis's team are understood to believe that the Commission should set out the legal basis for its demand.
Earlier this year a House of Lords committee concluded that the British Government had no legal obligation to pay such a bill.
Tory Eurosceptics have urged Mr Davis to go further and postpone any possible agreement on a payment until the EU agrees to open up talks on a future trade deal.
Jacob Rees-Mogg, the MP for North East Somerset, conceded that a payment could help to secure an agreement on continuing trade, but said: "We shouldn't be bamboozled by the Commission's wish to set the timetable."
Other rows are also expected to play out. The Commission is seeking guarantees that the European Court of Justice will maintain jurisdiction in Britain to guarantee the rights of EU citizens remaining in the country.
But the UK has formally rejected the demand, arguing that it would be unprecedented for the Luxembourg-based court to have direct jurisdiction over a non-member state.
Instead, a position paper published by Mr Davis's department last week outlines a series of alternative models, citing existing examples including Moldova, which has an arbitration panel that refers disputes over EU law to the ECJ.
The EU also wants to settle the question of an Irish border before substantial Brexit negotiations begin next month, with officials pushing for a hard border as part of any new customs arrangement. But in a paper the Government has said that it wants to avoid "any physical border infrastructure" between Ireland and Northern Ireland.
While Mr Davis is negotiating in Brussels, Theresa May is separately likely to be warned by political and business leaders in Japan that its economy could also be damaged by a "disorderly Brexit".
Mrs May is due to fly to the country on Wednesday accompanied by British industry chiefs. Ahead of her trip the influential Keidanren group of Japanese business warned: "Reflecting the complexity of the issues involved in the future relations after a period of transition ends, both sides should show further flexibility in order to avoid the ... worst scenario.
"The UK in particular is encouraged to recalibrate its basic position so that the final deal should avoid damaging not only the economies on both sides of the Channel, but also the world economy as a whole."