We look ahead to this year's Conservative party conference, and the one story that is sure to dominate proceedings: the battle between Boris Johnson and David Cameron.
This is a rivalry that has been longstanding, stretching back some believe to their school years at Eton.
Boris Johnson was two years Cameron's senior, and one of the school's academic elite. They both went on to Oxford University, where they were photographed as members of the infamous Bullingdon Club, and where it's said they both got on quite well.
Indeed, when Cameron became Tory leader in 2005, he rescued Boris from obscurity by giving him a minor role in charge of higher education policy. Three years later Cameron was enthusiastic in endorsing Boris in his successful bid to become London mayor.
But soon after Cameron became prime minister, things began to change. In October 2010, Johnson described the coalition's proposal to cap benefits at £21,000 a year as "Kosovo-style social cleansing," insisting the move would not be implemented "on my watch". Within two hours the prime minister's spokesperson had hit back, saying "Boris is Boris" but that "this time he has gone too far. To accuse the prime minister of social cleansing is well over the top".
It was the start of a very public deterioration in the relationship between Cameron and Johnson - and one that is expected to overshadow completely this year's Tory party conference. Here's why:
Round one: the third Heathrow runway
Just this week Boris renewed his attack on Cameron over the prospect of a third runway at Heathrow airport.
Suggesting the prime minister had been "bewitched" by airline lobbyists, the London mayor said he would tell BAA to "forget it". He also criticised Cameron's government for dithering on the expansion of the UK's runway capacity, warning the PM he would be "'tiptoeing towards a political electric fence" if he were to accept plans to expand Heathrow.
This is a political issue fraught with strong opinion from both sides, and while Cameron's response has been to commission the Howard Davies report in search of a solution to please all, to many - including Boris - this is seen as weakness and an inability to take decisive action on an issue which needs urgently to be addressed.
Round two: EU membership
Eurosceptic Johnson has long been a thorn in the side of the prime minister on issues over the UK's place in the EU.
For a long time Boris has been opposed to further ties with Europe, and has publicly resisted moves to increase binding economic arrangements. He's also been a vocal supporter of an in/out referendum to be held on the UK's EU membership.
But Cameron's feelings on the EU are less clear and seem to have been changing rapidly since his years spent in the ranks of Tory eurosceptics. He started out opposing a referendum, before deciding he was in favour, then finally announcing that he would campaign vigorously to keep the UK as an EU member.
While not everyone in the Tory party agrees with Mr Johnson's EU stance, at least he has made his views crystal clear - unlike the prime minister.
Round three: immigration
David Cameron's government has made clear its ambition to reduce immigration. it has introduced caps and has debated the rights of struggling Greeks to enter the country in the event of their removal from the euro.
But Boris has spoken often on his opposition to the Tory cap, which he says could have a damaging effect on the UK economy. Only this week he urged ministers to allow "the best and brightest to come here, contribute and thrive" as he applauded the establishment of a new cross-party immigration group, Migration Matters.
Round four: the living wage
While Cameron has endorsed the living wage - an alternative to the minimum wage which pays the lowest earners a liveable rate - Johnson has gone much further in practically supporting and implementing the move.
In July cleaners of Downing Street revealed they were paid just £6.95 an hour. They reportedly left letters on the desks of eight cabinet ministers, including David Cameron, asking for the living wage that so many have publicly supported.
In contrast Johnson has worked closely with Citizens UK, the main group behind the movement, to not only encourage London employers to pay the wage, but also in implementing it throughout the Greater London Authority.
Round five: Andrew Mitchell and 'gate-gate'
Another recent hiccup in Cameron/Johnson relations was the controversy caused by chief whip Andrew Mitchell, when he reportedly swore at Downing Street police who refused to open a gate for him.
Cameron defended the chief whip and ruled out an inquiry. But just as the media was beginning to lose interest, Boris brought it back into the headlines when he told journalists he though police were right to threaten Mr Mitchell with arrest.
The final round?
The scene is now set for a showdown at this year's Tory party conference. Boris goes into to the conference on the stronger foot. He has distanced himself from the government's policies of austerity and controversies like Andrew Mitchell, and as always is enjoying popularity based on humour, personality and some very distinctive hair.
By contrast, a recent YouGov survey for the Sun revealed only 13% of people think Cameron is doing a good job as leader, and 20% associate him with a snake.
As all parties begin looking towards the next general election, the struggling PM certainly has the most to lose. He is up against a London mayor who has consistently been rated higher in popularity and can always rely on a natural crowd-pleasing charisma.
So who will 'win'?
While the party faithful and the few still interested enough to watch a party conference speech will tune in for Cameron's performance, those looking for a cheap laugh and a funny photo for the next day's papers will have eyes only for Boris.
His gaffes and gags are sure to hit the headlines; but can he win heads as well as hearts?
While Mr Johnson's speech will inevitably be more entertaining, will he fill it with substance?
If he can pull out the bag a speech with humour and wit as well as sensible policy then Cameron could well be in real danger. But in all likelihood Cameron will provide the policy, while Johnson continues with the stand-up routine.
However, if the pair aren't careful to control this double-act there could be an outside winner to this embarrassing old-Etonian feuding, and that's someone who also went to the same school as Mr Johnson: Ed Miliband.
You can watch both speeches live here on MSN. Boris is up on Tuesday at 11.00am, and Mr Cameron the following day, Wednesday, at 11.15am.