Juan Pablo Montoya [Images] is the talk of the French Grand Prix, without even being present.

The Colombian's stunning decision to join NASCAR next year prompted McLaren to release him immediately and promote Spanish test driver Pedro de la Rosa to the line-up for Sunday's race.

While Montoya stays at home in Miami [Images], preparing for a new start with team owner Chip Ganassi, the shockwaves will reverberate at Magny-Cours.

There are plenty of questions -- about just how hard Montoya is going to find the leap from Formula One to the rough and tough U.S. stock car series, and about his likely long-term successor at McLaren.

Formula One is short of swashbuckling characters and Montoya, a man with no shortage of attitude on and off the track, will be missed by commentators if not by his fellow racers.

There will also be further analysis of his mercurial nature and Magny-Cours is as good a place as any for that.

It was here three years ago that Montoya had an extraordinary row with Williams that precipitated his switch to McLaren.

Towards the end of the 2003 French Grand Prix, Montoya accused bosses of favouring team mate Ralf Schumacher at a pitstop and launched a tirade of abuse over the car radio for 10 minutes before sulking and then slowing down.

He was reprimanded at a meeting days later.

NOT IMPRESSED

"I think Juan was not impressed at having his knuckles rapped and I know the decision to sign with McLaren was taken within a few days of that," team co-owner Patrick Head was later to recall.

"Finishing second behind his team mate does not make him a happy lad," he added.

"Juan is a passionate character and by virtue of that he sometimes makes impulsive decisions and comes to impulsive conclusions."

The criticism he got for crunching into the back of team mate Kimi Raikkonen's [Images] car seconds after the start of the U.S. Grand Prix in Indianapolis this month may have triggered another such moment.

There were already rumours, swiftly denied, kicking around on Sunday afternoon at Indianapolis that Montoya would be dropped for De la Rosa.

Whatever, Montoya was consistently outshone last year by Raikkonen, who had seven wins to the Colombian's three, and his form this season has not been anything to shout about.

For a man who does not do self-doubt, that hurts.

His Formula One story, with seven wins and 13 pole positions in five-and-a-half seasons, was increasingly looking destined to be one of raw promise and unfulfilled potential.

Montoya's chances of securing a race-winning car, or indeed any grand prix car, next year were drying up. The decision to join NASCAR gives him a fresh start and also takes him back to his roots.

Of all the drivers in Formula One, Montoya appears best suited to the switch and not just because of his eagerness to bang wheels with rivals and re-arrange the bodywork of his car.

He raced on ovals in CART, where he was champion in 1999, but even so he will have his work cut out to readjust to his new environment.

As Montoya said in a teleconference with U.S. reporters on Wednesday, he will have to get used to being bumped from behind and bumping others. He will also need to learn a different racecraft.

"(It will be) getting used to running side-by-side with a car beside you for 20 laps or 100 laps...learning when to draft, learning when to move out of the draft, learning when to go high (on the banked ovals) and when to go low," he said.

"When I raced CART before, people used to go high, but I was watching a replay of the Daytona race and Chicago race, these guys run so close to the wall it's not even funny. That's going to take a lot of practice.

"I know the team is going to be very patient with me. It's going to take time and we're all in it together for the long run."

If all goes to plan, Montoya will be able to look back in future years and say he was a winner in the Indy 500, CART, Formula One and the Monaco Grand Prix and NASCAR.

It would be a resume unlike any other in motorsport and the Colombian has no regrets about his decision.

"Moments come in your life and you can either take them or leave them," he said. "I decided to take it."

• Formula One coverage