Boris Johnson and David Cameron will lock horns over lunch at Chequers later today as the Prime Minister attempts to get the London Mayor in line ahead of next weekend's Tory conference.
Mr Johnson is said to be "relaxed" about his first visit to the Buckinghamshire residence and the pair's "wide-ranging discussion."
They will be joined at the meal table by their wives, Marina Johnson and Samantha Cameron.
Despite Mr Johnson's denied ambitions to succeed Mr Cameron, his two keynote speeches at next week's highly-charged conference in Birmingham will be watched closely for signs of potential leadership positioning.
Mr Johnson recently clashed with the Prime Minister over airports in the South East, accusing the premier of paving the way for a U-turn on Heathrow's third runway, while Britain's role in Europe remains another possible flashpoint.
The Mayor also won little favour at Number 10 for saying police showed "common sense" when they considered arresting Chief Whip Andrew Mitchell following his angry confrontation with police at Downing Street.
Mr Cameron has refused calls to order an inquiry into the incident.
Yet asked during his trip to Brazil last week if he felt threatened by his fellow Old Etonian, Mr Cameron replied:
Not at all. Boris has been a great friend of mine for a long time and a first class Mayor of London.