It also re-arranged the complexion of the F1 world championship!
For this is the simple truth: the Spaniard's unforced error let Kimi Raikkonen back into the title hunt. Instead of extending his lead over the Flying Finn by two points, Alonso's lapse resulted in a 12 point swing - two more points for Kimi, and 10 fewer for Fernando.
So, the mathematics nicely equals out the 12-point swing of the previous race, at the Nurburgring, where Raikkonen's suspension collapsed 90 seconds prior to what would have been a famous victory.
The net result of it all is that Alonso has protected the margin he had over Raikkonen after Monaco - but with two races less to go, his grasp on the trophy has effectively been strengthened, albeit only marginally.
That's what the percentage figures would like to tell us, in any case. But F1 is a far more complex beast than simple mathematics.
A myriad of almost incalculable factors regularly terrorise the best laid plans - unfathomables such as the weather, air temperatures, track temperatures, tyre wear, asphalt conditions, driver errors, other drivers' errors, safety cars and mechanical reliability, to name but a few.
Mika Hakkinen and McLaren, for instance, effectively lost the 2000 world title in the first two races, through a crankshaft failure in the second race, and a filter failure in the first.
A regular little filter, costing a couple of pennies!
So what's in a couple of millimetres? Not much, unless you clout a wall, like Alonso did in Canada.
For more than letting Raikkonen back into the hunt, he has also opened the door to Michael Schumacher. And the Schu, as we know, is at his most dangerous when he's chasing, with nothing left to lose.
Granted that the champion's chances of defending his title successfully are very slim indeed. But it's not totally over yet. And if he is presently at the tail end of the title trio, Schumacher and Ferrari will draw hope and inspiration from Barrichello's drive on Sunday.
Ending on the podium after having started in the pits is good going, even though two Renaults, two BARs, one Williams and one Toyota had dropped out - which ain't gonna happen every single time.
But it's not gonna happen every single time either that Rubens is gonna start from the pits.
The Schu is still alive
The point of all this is rather that Schumacher is still alive, courtesy of Fernando's faux pas. Yes, Michael still has two tough competitors to catch, both in class-of-the-field cars, at least for the moment - and unfortunately for Michael, this "moment" will probably extend straight into Indianapolis and possibly a little bit beyond, too.
It's called momentum, something Renault and McLaren have plenty of, right now. And it's a good time to have it; the F1 calender stages five races from now until the end of July, three of which are crammed into 21 days, starting on Sunday at Indy.
Which doesn't leave a lot of time for development work in between.
Which should favour the form players.
Which are Renault and McLaren.
Assuming, then, that a couple of drivers will have an edge over the Schu at Indy, one could work on the assumption that Alonso will start the second half of 2005 with a 40 point advantage over Schumacher. Which means that Michael will have a maximum of 10 races in which to reverse a massive deficit.
This will require:
1. That he dominates from France onwards, in the way that Alonso has dominated over the first half of the season.
2. That Alonso under-performs from France onwards, as badly as Schumacher has up to now.
The first is highly improbable - although not impossible. If Bridgestone comes up with an answer, Ferrari might well start winning again, especially after the summer break.
The latter, though, is almost unthinkable.
How many points could really be made up in half a season, in any case?
James Hunt won the 1976 title from Niki Lauda after trailing by 45 points at one stage. So let's say that a deficit of 40 might just be possible to catch then, with a lot of luck. But 50 seems to be a bridge too far.
So, instead of having locked the Schu out of the 2005 chase completely on Sunday, Alonso created an infinitesimally small opening for the Maranellan driver to stick his dangerously red boot into.
Michael, as a matter of fact, is not that far behind Raikkonen - although Kimi, by rights, should have been a further 26 or 28 points up the road, were it not for a tyre valve failure in Malaysia, a CV-joint failure at Imola and that flat-spotted tyre at the Ring.
Schumacher then, will be praying for a good break over the next three weeks. If both Renaults and McLarens beat him at Indy and Magny-Cours, F1 will crown a new champion at the end of 2005 - and either of them will be a worthy champion.
Raikkonen is a tremendously cool customer, with loads of high-tensile steel in his soul.
And Alonso is strong and determined, if not equally unflappable over the coarse of a season.
Not yet, in any case. The Spaniard's Montreal mistake was totally unnecessary, on more than one front.
Firstly, he seemed to have lost his composure behind Fisichella, who was holding Alonso up.
Now, Fisi was quicker in quali, quicker off the line and leading the race, which put him in position to control proceedings while protecting his tyres and brakes for the later stages.
But because Giancarl"
1. Has no chance of winning the championship any more and
2. Was slower than Fernando, who
3. Is not exactly cruising to the title by any manner of means, the Spaniard obviously felt that
4. He could legitimately expect some kind of team play, if not team orders.
Is this not, heaven forbid, the modus operandi of the world's most successful racing outfit ever?
Well, there have been differences between the Scuderia on the one hand, and la Regie and McLaren on the other.
Fisi has had all the bad luck at Renault thus far in 2005, as Montoya has had all of McLaren's.
But suffering this type of curse for five months is completely different to having been burdened with it for five years, as has been Barrichello's fate at Maranello.
Again this year the mechanical failures seem to plague only his F2005, with major gearbox problems in three of Ruby's five races with the new car thus far.
And this weird pattern of Barrichello break-downs over the first half of a season - until Ferrari is left with only one true championship contender, after which Rubens has no choice but to support Schumacher - has repeated itself now, without fail, for five years in a row.
Rubens, in fact, is contractually bound to support Schumacher; Fisi and Juan are not in a similar position vis-à-vis Alonso and Raikkonen.
Therefore they will race for the win whenever they can, up to a point where it makes more sense to play the team game.
The question Alonso will therefore ask is: Has that point not already arrived?
Even though it is relatively early in the season, Renault clearly has only one contender left in the title race - as has McLaren. Alonso, in fact, has already asked the question, shouting it out over his radio in the race itself.
Kimi not intimidated
Kimi, on the other hand, has not. And he will not. He's not that kind of character.
Raikkonen is almost insular in his willingness to fight the field - including his teammate - all by himself. What he expects of the team is a good car; the rest is up to him. And if he comes short, he is more than willing to shoulder the blame.
After the Ring he was resolute in his acceptance of having flat-spotted the tyre. And resolute in his acceptance of having made the decision to carry on, gambling on a win.
"I have no one else to blame," he declared. Coolly. Factually. Emphatically.
In the process he again embodied the spirit of a true racer, boldly and fearlessly.
Remember how Kimi had kept his foot planted in 2001 through Eau Rouge, after Panis had blown up and gone off in a cloud of smoke?
Or how he had battled Montoya at Hockenheim, through a sequence of half a dozen corners; hard but fair, without budging an inch?
Or how he had passed Schumacher last year on the outside of the entry to Eau Rouge, pedal to the metal?
Here is a guy - same as Montoya and Alonso - who truly lifts the sport to where it belongs, in the domain of the fast and the furious.
Schumacher is also ever so enthusiastic about real speed. And he is forever close to his personal edge.
But over the years he has failed the game in one very important aspect, and that is to race a worthy teammate.
Raikkonen is clearly not intimidated by this kind of possibility. Even with suspect steering he started to reel Montoya in hand-over-fist towards the end of his second stint in Canada. A victory for him might have been on the cards in any case, Juan's pit stop debacle notwithstanding.
Had he been beaten though, he would also have been big enough to accept it. After the race, he candidly admitted that Montoya was quicker than him at certain stages of the race. These truths come to Raikkonen like everyting else, naturally and steadfastedly.
Montoya, of course, is fantastic in manos-a-manos duels. He is the ultimate swashbuckling buccaneer.
Look at how he overtook Kimi last year in Brazil. Or the Schu on the outside of the bus-stop, at Spa.
In fact, he has put more moves over Michael than the seven times champion would care to admit.
But Montoya's also Latin. He has a certain type of casual, candid openness about him. At times, he can be positively disarming with an innocent, almost childlike kind of honesty.
But he can also misread a situation, mislead himself and let his anger rule his mind.
Missing red because you are seeing red can lead to a black flag - and the end of your season. From here on in, Juan simply cannot come back.
Which leaves Alonso, a slightly different character, less impulsive than Montoya, but still flamboyant and also Latin - and therefore not totally as unperturbed as the Ice Man, although he has driven superbly well this year, in all kinds of circumstances.
That is, up to Canada, where he made an unnecessary mistake that could, in the final reckoning, cost him the title as well as the honour of becoming the youngest F1 champion ever.
And Fernando made that mistake, firstly, because he lost his composure behind Fisichella - which is understandable. But he also made the mistake because he was determined to win - which was less understandable.
For this is the truth: Fernando had points to play with. He could have taken second or third, and still have led the championship handsomely.
But it is the psychology of it all, you see. Alonso might be as surprised as we are to see Renault equalling the mighty McLaren for pace this deep into the season.
Viry-Chatillon (in France, where the RS25's engine is built) and Enstone (in England, where the car's chassis is built) run on half the budget of the big teams. The time will therefore come, sooner or later, for McLaren to really get the upper hand.
So, for Fernando, it was a case of striking when the iron was hot.
He could have - and probably should have - driven defensively. Renault would in fact already have considered switching to a less radical programme of car development for the rest of 2005, concentrating more and more on reliability.
And Alonso - as Bahrain, Imola and Monaco have shown - is superb at driving defensively.
But one look at how he attacked when he smelled blood at the Ring also confirms that the young Spaniard is a real conquistador at heart. As is Raikkonen. And Montoya. Who is not going to back off for Kimi.
We have a couple of twists and turns to go yet, in 2005.
Egmont Sippel is the motoring editor of Rapport
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