By Andrew Benson
Juan Pablo Montoya's decision to quit Formula One for the US Nascar stock-car series is a terrible shame - for both the driver and F1.
Montoya brought rare charisma and flair to Formula One
The 30-year-old Colombian may not have had the best of seasons with McLaren this year, but his departure will leave a void in the sport.
It is difficult to know the real reasons for Montoya's decision, but it smacks a little of impetuousness.
His options in F1 for next season were limited, and he appears to have decided that rather than face an undignified search for a drive in a middling team, he would go off and race somewhere he was appreciated instead.
But it is the impulsiveness in Montoya's character that makes him such an inspiring, appealing and dynamic racing driver and personality - and that is what will be so badly missed.
His incredible skills at overtaking - to which he brings an improvisation, bravery, deftness and flair that has arguably never been seen before - are inseparable from his mercurial character.
It is easy to forget that until Montoya's arrival in the sport in 2001, overtaking in modern F1 was considered so difficult as to be almost impossible.
That is still the case, but Montoya has been able to transcend the limits imposed on drivers by complex aerodynamics and shorter braking distances and pull off passing moves that can only be described as breathtaking.
Montoya's skills attracted fans from across the world
The fact that no-one else has been able to emulate him merely underlines his astonishing ability - he will probably be remembered as the best overtaker in F1's history.
On a personal level, he is also a breath of fresh air - chatty and outspoken where many drivers are monosyllabic and conformist; charismatic when many are uninspiring.
For all the awesome genius of Fernando Alonso and Michael Schumacher, F1 needs this kind of maverick for the sake of its public appeal.
But Montoya's mercurial nature also carries over into the cockpit, and this is where it has all gone wrong for him in F1.
On his day, there is no doubt that he is at least a match for anyone on the grid, as he has shown on numerous occasions during his seven Grands Prix victories and with his amazing passing moves.
But just as the most inspirational footballers cannot produce their best form in every game, so Montoya, too, has his off days - too many for one of his ability, some would argue.
So, while in the second half of last season Montoya overshadowed his McLaren team-mate Kimi Raikkonen, this year has not been so good.
Montoya made too many mistakes for a driver of his ability
There are reasons for this: he struggles badly with a car that lacks front-end grip, exactly the problem that has afflicted this year's McLaren.
This often happens with Montoya - if the car is to his liking, he is sensational; if not, he can fade into the background.
He is far from unique in this but what has harmed him more is that his propensity for making mistakes, which was always there, has not reduced as he has grown more experienced.
At a time when the F1 points system has led to consistency being prized above all, perhaps this is why Montoya was struggling to find a top drive for 2007.
With Michael Schumacher still not clearing up whether he will retire, the F1 driver market is stalled.
McLaren, having already signed Alonso, were in no hurry to say who they wanted to partner him.
With Raikkonen believed to be moving to Ferrari, Renault and Red Bull apparently showing little interest, and Honda and Toyota ready to stick with their current drivers, Montoya was facing a big step down in 2007.
And yet on an objective level it seems astonishing that no decent team could find a place for a man who most would class as among the leading five drivers in the world.
Montoya made his reputation with a series of superb overtaking moves
Tired of waiting for the teams to sort themselves out, Montoya decided to jump first and take his undoubted talent and colourful personality to Nascar, where they will be appreciated.
As a winner of the prestigious Indy 500 and the Champ Car title, Montoya is already highly regarded in America.
Nascar is hugely popular in the US, where Montoya already has a home in Miami, and it contains some great drivers.
But its staged close finishes and overwhelmingly showbiz approach seem somewhat beneath a driver of Montoya's ability.
Doubtless he is being handsomely rewarded for his switch, but it would be surprising if, deep down, Montoya did not share that view.
He will leave F1 with a whiff of unrealised potential, his reputation diminished by the way his career there has ended.
But that works both ways. F1's inability to find room for his idiosyncratic, yet unmistakable, brilliance makes it poorer, too.