I was beginning to feel pleased with having got ahead of Michael at the start when 'twoosh!', a red and white car suddenly came alongside. 'That'll be David,' I thought

The San Marino Grand Prix was significant because it was the first time this season that the Rothmans Williams-Renault team had not been dominant during qualifying. It was clear from the word go that Ferrari was going to provide tough competition and that proved to be the case. It was therefore all the more gratifying to win on Sunday; it had been a very tough test for the entire team and we came through with flying colours.

With Michael Schumacher starting from pole position and likely to give us a difficult time, we had to think long and hard about tactics. It was essential to work effectively as a team while doing our calculations and making plans, and for that reason, I'm really pleased that we came out on top. There was a tremendous sense of satisfaction. We had been working towards this over the winter and here was the chance to prove that the Williams-Renault team has got everything it needs: the best personnel and the right mentality to tackle a race such as this.

We chose the perfect tactic by running a long stint - almost up to half distance - before making the first of two pit stops. The tactic was devised by the team after detailed examination of all our options. I must admit I had my doubts at first. Fifteen minutes before the race was about to start, I was still in the debrief room going through it with Adrian Newey, the chief designer, to make sure the plan was plausible.

The new strategy obviously posed many pros and cons. On balance it made sense, although I have to say it would have been very easy to bottle out and adopt the familiar tactic of stopping at one-third and then two-thirds distance. But the more I thought about it, the more it became clear that this was actually a very good plan. I was helped by the fact that the car had been great during the morning warm-up. Although we didn't get it right during qualifying, we had established a good set-up on the car for the race. I was very confident going to the grid.

I was beginning to feel pleased with having got ahead of Michael at the start, when "twoosh!", a red and white car suddenly came alongside. "That'll be David," I thought. Sure enough, David Coulthard, repeating his great start from the previous Sunday in Germany, went steaming into the lead. I wondered how long he could maintain the lead with so much competition from behind.

A more immediate problem concerned my brakes; I had to be careful in the early laps because of the extra weight of the car due to the full load of fuel for that long stint, and yet I was loath to drop back too much. At the end of the first lap, I did not make a very good exit from the last corner. Schumacher, who was running with less fuel on board, was able to challenge going into the next corner. I gave him a bit of clearance to go through, in the knowledge that if I could stick with the Ferrari, then I had to be in with a shout. It was very difficult to judge the best pace. I couldn't afford to drop back too much and yet I couldn't drive too hard because that would either blister the tyres or wear out my brakes.

After a few laps I found a good rhythm and began to push harder and harder. I was in communication with the team throughout the entire race; plenty of discussion over the radio as to what was going on and who was where. We knew the critical period would be between Schumacher disappearing into the pits at one-third distance and the subsequent 10-lap gap to my first stop.

I had to give it everything and try to eke out an advantage while I had a lighter fuel load. I set the fastest lap of the race, but I had one or two moments when the car nearly got away from me. Although I was very close to the limit, I don't believe I was ever forced to go to the maximum. Imola is a very bumpy track; it is physically hard on the driver. You have to brace yourself very firmly, but even so, you get knocked about quite a bit. There are a lot of very fast entries to extremely tricky sections, which means it is easy to make a mistake.

On top of that, I had taken off quite a bit of wing angle. That meant the car felt very light while cornering, but it was faster in a straight line. I didn't want to struggle while trying to pass backmarkers as I had to in Germany the previous week, although on one occasion traffic cost me a bit of time, which I could ill afford because I knew it was going to be very, very close when I rejoined after my pit stop.

The pit stop was perfect and I got out just ahead of the Ferrari, but I had the benefit of new tyres. Our fuel loads were now similar and I knew from my experience in the early laps that I should be able to stay in control. In fact, Schumacher was not that much slower, an indication that we are likely to face stiff competition from Ferrari for the rest of the season. Gradually the gap opened and, later on, luck was on our side when I had a clear track and Michael was held up by the battle between Mika Hakkinen and Pedro Diniz.

We were brilliant as a team and we did the right thing all the way along the line and my fourth win of the season has put me back on the right course for the championship. I have to admit, however, that the title will not be my prime thought when we go to Monte Carlo in two weeks' time.

Monaco stands alone as the greatest test a racing driver can face in his career and the Williams-Renault team has not won there since 1983 with Keke Rosberg. I've never won there, despite the fact my father won it five times. I have my sights set on victory in this race.