Hamilton and Button have a lot at stake this season
By Mark Hughes
BBC F1 commentary box producer
The pairing of Lewis Hamilton and Jenson Button at McLaren this year is potentially explosive.
Both have an inner certainty that they are the best in the business - but they can't both be right.
In the past, pairings of two megastars in a race-winning car have resulted in volcanic fall-out. As one of those drivers is presented with stark evidence that fails to meet with his own inner certainty, so things tend to get very difficult - and the driver on the losing end tends never to be quite the same again.
That's what's at stake here for either Button or Hamilton.
History gives us clues of how things might shape up - think Hamilton/Alonso in '07, Prost/Senna '88-'89, Mansell/Piquet '86-87.
When Alonso switched to McLaren for '07, and a rookie started going faster in the same car, "Does not compute" signs would have been flashing in his mind
Such competitors have an inner conviction they are the best and usually everything in their careers has served only to reinforce that view.
They know that when it comes to it they can squeeze something extra from the car, know they have access to a level of performance out of reach to the others, that in equal machinery they can beat anyone.
That conviction is not usually damaged by uncompetitive cars because that can be rationalised quite easily. Not so easy is to reconcile another guy going faster in the same piece of kit.
Fernando Alonso is a good case study.
Utterly magnificent in his two championship years of 2005 and '06, the second title was particularly sweet in that it came after a season-long gloves-off fight with seven time champion Michael Schumacher, the long-accepted barometer.
Alonso's evenness, the way he always held himself in full control, always seemed to do the right thing, was very evident in that battle.
He made not a single mistake worthy of the name all year - even more impressive than his solitary mistake at Montreal the year before.
By contrast, Schumacher occasionally over-reached in that final season with Ferrari - the wheel-banging in defence at Hungary that damaged his suspension; the attempt at out-qualifying his team mate in Turkey despite a massively higher fuel load that led simply to a botched lap and losing; the infamous parking incident at Monaco.
Both Alonso and Schumacher ended 2006 thinking they were the best
It may have been no more than Schumacher knowing he had to be more aggressive because he was always fighting against a points lead established by Alonso early in the season.
More likely, it was just the differing traits of two awesomely good drivers in the hard grind of a championship battle.
But it's unlikely Schumacher's inner conviction was damaged by that season - or even at Suzuka in 2005 when Alonso went around his outside through 130R at 208mph.
Because they were in different teams and cars, there would always be a justification in Schumacher's mind if he was beaten. For all we know, he may have been right.
Schumacher will have gone into retirement being able to tell himself that he was still the number one - and had never been threatened in that status.
Part of what had enabled him to do this, aside from his fabulous talent, was his dominant position within Ferrari, with team-mates that were very carefully chosen and then controlled when necessary.
The whole team was focused around Schumacher so they as a team could take on and beat the rest. The team-mate was part of the support for that and never allowed to be a genuine rival.
Alonso equally could justify to himself that he was now the top man.
You can bet Hamilton is relishing the battle with Button - and also that he's totally confident he will prevail
He had won two consecutive titles against Schumacher, the last of them when Michael was in a very competitive car. He had also put that marker down on him at Suzuka in '05.
With the title already secured and nothing at stake, he had committed to going around the outside of Schumacher in a manoeuvre that, if it had gone wrong, would likely have been fatal.
He had every reason to feel good about his standing - and the fact that Michael had retired meant surely he was now even more clearly the world's number one. Once it had been Senna, then it was Schumacher and now it was Alonso.
So when he switched to McLaren for '07, and a rookie started going as fast or faster in the same car, it will not have tallied. "Does not compute" signs would have been flashing in his mind.
Alonso was unfortunate indeed that his reign as the sport's unquestioned number one had lasted only for as long as the off-season, but the reality was simply that he had been paired with another of comparable ability in a team that operated very differently from Ferrari.
We got to see the effect of such an affront to his self-belief - paranoia.
Alonso found it hard to deal with Hamilton beating him in 2007
For Hamilton to be challenging him, he reasoned, he must be getting preferential treatment from the team and it all sort of fitted - Hamilton had been part of the team since he was 13, knew everyone there already, was a Brit in a British team etc.
In Spain, in front of Alonso's home crowd, the idea of being beaten by Hamilton was just too humiliating to contemplate. So he fuelled lighter to qualify ahead, then tried a no-compromise first-corner move on Felipe Massa's Ferrari that was never going to work - and off he went across the gravel trap.
In Montreal, as Hamilton sailed off to his maiden grand prix victory, Alonso made a catalogue of errors - more in one afternoon than he had made in the previous two seasons combined.
He had badly lost his equilibrium and his horribly ill-advised tactic of trying to use the FIA McLaren espionage investigation to his advantage ensured he no longer had a long-term future there.
That whole situation would never have arisen had Hamilton not had the raw performance to threaten Alonso's internal view of his standing. He wasn't always slower than Hamilton of course - beat him fair and square on occasion. But he was beaten by him regularly enough for Alonso not to be able to handle it.
Hamilton had exactly that certainty of being the best. He could easily justify to himself those occasions when Alonso beat him: his team-mate was in his sixth season of F1 whereas Lewis was a rookie.
If ever Alonso was faster, that was why - in Hamilton's mind.
At Monza and Spa, Alonso defeated Hamilton conclusively on two consecutive weekends. Hamilton reacted by going back to the factory and spending a couple of days trawling through set-up data and analysis with his race engineer.
"I now understand why I was a bit slower than Fernando at those races," he said, "and now I've understood that I'm confident I will back to my best."
Impressively, he then proceeded to dominate everyone - including Alonso - at the next race at Fuji. So his internal reasoning of his standing was reinforced.
Alonso's contract was duly cancelled two years short of its term and the team effectively became Hamilton's. It was perhaps the most astonishing seasonal performance from a rookie the sport had ever witnessed.
Alonso was banished to an uncompetitive car in 2008 and '09 but with a fast Ferrari under him for 2010, we get to find out if he can scale his pre-Hamilton heights again.
Of course he will be fast, but will we ever again see the driver that made that move on Schumacher? Did that season alongside Hamilton damage him or not?
Hamilton, meanwhile, is flying high. No one, not even a double world champion with a six-year head-start, has been able to get the better of him.
He completely decimated a good team-mate in Heikki Kovalainen in the way that Ayrton Senna used to decimate good team-mates. Now he gets Button, 2009 world champion, to be judged against.
You can bet Hamilton is relishing it - and also that he's totally confident he will prevail.
For his part, Button spent almost a decade in sub-standard cars, having arrived in F1 perhaps a little too early. But his inner conviction of his worth was established long ago - when he was invariably the dominant man throughout his karting career.
He has a karting CV that's actually more impressive than Hamilton's. When he finally got himself into a good F1 car last year, he delivered the world championship. In his mind, that will all tally.
Now, the next challenge of going into the perceived number one driver's own team and taking him on.
He didn't need to make that choice, could have stayed where he was, assured of a competitive car and been protected from any doubt if Hamilton's McLaren had beaten him - in that he was in a different, obviously not quite as good, car.
His very choice of opting instead to walk into the lion's den tells you everything about his own inner confidence of his level.
Both sets of beliefs - Hamilton's and Button's - cannot survive this season.