Boris Johnson will have lunch with David Cameron at Chequers in the wake of a series of clashes.
The Prime Minister is understood to have invited the London mayor for a "wide-ranging discussion".
It is believed to be Mr Johnson's first time at the premier's Buckinghamshire residence. His wife Marina and Samantha Cameron are also expected to attend the meal.
Sources said the Mayor was "relaxed" about the lunch, which follows a personal invite from Mr Cameron two weeks ago. He has apparently been invited before, but diary commitments meant he could not accept.
The engagement comes just a week before the start of a potentially highly-charged Tory conference in Birmingham. Mr Johnson is due to make two keynote speeches at the gathering - which will be watched closely for signs that he is "on manoeuvres" against the party leader.
Mr Johnson recently clashed with Mr Cameron over airports in the South East, accusing the premier of paving the way for a U-turn on Heathrow's third runway. The Mayor favours building a brand new airport in the Thames Estuary, dubbed Boris Island.
Mr Johnson also intervened after Andrew Mitchell, the Chief Whip, had an angry confrontation with police guarding Downing Street during which he allegedly called officers "plebs". The Mayor said the police showed "common sense" when they considered arresting the Chief Whip. Mr Cameron has refused calls to order an inquiry into the incident.
Europe is another possible flashpoint. Mr Johnson has backed demands from the Tory right for an "in-out" referendum on Britain's membership of the EU, while the Prime Minister has so far resisted pressure to promise one. He has, however, suggested that a vote could be held at some stage after the next general election in 2015.
Mr Johnson has flatly denied ambitions to succeed Mr Cameron. Some Tories, however, want him to try to return to Parliament before the 2015 election so that he would be able to launch a challenge for the leadership.
On his trip to Brazil last week Mr Cameron was asked if he felt threatened by his fellow Old Etonian. He replied: "Not at all. Boris has been a great friend of mine for a long time and a first class mayor of London."