Boris Johnson and Jeremy Hunt are preparing to take part in their only scheduled head-to-head encounter of the Tory leadership campaign.
The two contenders to succeed Theresa May as the British Prime Minister will appear on a live TV debate on Tuesday which could help to decide the outcome of the contest.
Mr Johnson will hope to use the occasion to seal his position as the clear frontrunner, with polls giving him an overwhelming lead among party members.
For Mr Hunt, the UK Foreign Secretary, it potentially offers a final chance to turn around a contest in which he has been the underdog throughout.
Although both men have taken part in numerous hustings - where they take questions separately from party members - Mr Johnson has agreed to take part in only one previous TV debate, when there were still five contenders left in the race.
It appears to be part of a safety-first strategy by his advisers who fear a gaffe could cost him a race which would otherwise be in the bag, leading to accusations that he has been running scared.
Mr Hunt has been particularly critical of Mr Johnson's unwillingness to subject himself to more detailed scrutiny earlier in the contest.
Ballot papers started going out last week to the party's estimated 180,000 members, and many will already have voted, meaning that the potential for the debate to alter the course of the contest may be limited.