When Robert Kubica stormed to a podium in only his third Grand Prix start, it became apparent that a significant new talent had arrived on the F1 scene. Kubica, remember, was not driving for a truly front-running team - this was not like Hamilton finishing 3rd on his debut for Mclaren. Until Monza 2006, BMW Sauber had picked up just one podium - at a high-attrition Hungarian Grand Prix. For this Polish kid who, unlike most of the sport's, young pretenders, had not come up through the GP2 ranks, a podium wasn't merely delivering to expectations - it was getting far more out of the car than anyone had expected.

Whether fortunately or unfortunately, he chose the day of Michael Schumacher's retirement to make his presence known, and as such, his drive didn't get perhaps the same kind of attention as, say, the German's own debut in a Jordan way back in 1991 at Spa. Unfortunately? Well, a driver's stock is only partly about results. Perception counts for all too much, and one can't help feeling there would have been a bit more of a buzz about Kubica had he not picked up that impressive 3rd place on the day of Michael's retirement.

On the other hand, he was perhaps lucky that the paddock's attention was focused elsewhere. 2007 was a bit of a disappointment, all told. Sure, he was far from hopeless, but to everyone's surprise, it was comparative veteran Nick Heidfeld who was the quicker BMW driver last year.

It was a textbook example of the futility of trying to rate drivers in absolute terms. Is Kubica faster than Heidfeld? I think he was when the BMWs were on Michelins. When they swapped to Bridgestones, the German had the edge. Seemingly, Kubica just did not have the confidence in the car that he needed. Remove engine braking and traction control, and the situation has reversed again. Now, though, it is Heidfeld who doesn't feel at home in the car, while his young team mate has really begun to make the kind of impact people like me thought he would right from the moment he made his debut at the end of 2006.

And so it is that, following a maiden victory in a chaotic race at Montreal, Robert Kubica is now four points clear of the chasing pack of Raikkonen, Hamilton and Massa. Now, as I explained at Motorsports Ramblings last week, I'm something of a fan of the Pole, but I doubt he'll be able to hold his position to the season's end. Don't get me wrong, he's quick, but the BMW is still at least a couple of tenths off the pace of the Mclarens and the Ferraris and that should mean that on a day when Maranello and Woking get it right, Kubica is going to have to do something pretty special to finish better than 5th.

So is it luck alone that has propelled him to the head of the driver's points table? Not at all. Each of the three supposed leading contenders has made mistakes that cost points. Raikkonen ran into the back of Sutil in Monaco and ended up pointless. Massa spun out of second in Malaysia and might have finished second in Monaco had he not speared on up the escape road in the wet early on. Hamilton made a mess of his Bahrain weekend and eliminated himself (and Raikkonen) in humiliating fashion in Montreal in, what Clive at F1Insight described as "a perfect demonstration of the classic traffic light rear-ender."

Kubica, by contrast, has made no such mistakes. His only non-finish came in the opening race when he fell victim to a braking error from Kazuki Nakajima. Indeed, while everyone was raving over Hamilton and Sutil's drives at Monaco a fortnight ago, it is worth remembering that, while Hamilton clouted the wall early on and Sutil passed cars under waved yellows, Kubica (like Webber) did not put a foot wrong all afternoon and got about as much as anyone could have done with what he had.

Of course, the one thing Kubica has not yet had to cope with is living up to the pressure of raised expectations. When Hamilton was overachieving against Alonso early last year at Mclaren, he made no mistakes while his double World Champion team mate appeared on occasion (most notably at Montreal) to crack under the pressure. Hamilton's errors crept in only at the end of the season when the World Title was his to lose. This year, carrying the hopes of Mclaren and Mercedes on his shoulders, he seems not to be so impervious to pressure. It will be interesting to see how Robert Kubica copes now he has established himself as a Grand Prix winner and Championship leader...