Zanardi took his first win from pole position ahead of Félix Porteiro with Alain Menu's Chevrolet in third to complete the podium.

At the start Porteiro came up from third to take the lead into the first corner as Tiago Monteiro clashed with Gabriele Tarquini, which caused him to lose places.

Chevrolet's Robert Huff also lost places but James Thompson had a good start, moving up to sixth to fight with Huff on the first lap and he soon managed to overtake him.

During the rest of the race Huff lost further positions to Yvan Muller, Augusto Farfus and later Jörg Müller.

Another Brit to struggle in the race was Andy Priaulx who, unlike the other BMW cars, seemed to lack pace and ended up battling with the independent drivers in the closing stages.

Zanardi and Porteiro began the race from the front and remained there throughout, ahead of Menu.

However, midway through Porteiro was struggling with understeer and handed the lead to his team-mate who had more speed in his car.

The top three drivers eked out a seven second lead over the rest of the field by the chequered flag.

Farfus and Jörg Müller, who made their way through the field from eighth and fifteenth, to finish fourth and fifth demonstrated the potential of the BMW cars.

Yvan Muller who was eighth in race one will start from pole for race two with Thompson alongside him after finishing seventh while Gabriele Tarquini earned a sixth place that enabled him to stretch his championship lead to 11 points.

The Independents' class was fiercely fought. Pierre-Yves Corthals led them through the first lap but was overtaken by Franz Engstler and Sergio Hernández, who went on to fight for the win.

Hernández eventually crossed the line ahead, but only just as he had to weave across the line to keep the German behind him.

Stefano D'Aste crashed into the barriers on the final lap.

Race one results:

1. Alessandro Zanardi (ITA) BMW 21mins 55.769secs

2. Felix Porteiro (SPA) BMW 21:56.594

3. Alain Menu (SWI) Chevrolet 21:57.476

4. Augusto Farfus (BRA) BMW 22:05.245

5. Jorg Muller (GER) BMW 22:07.953

6. Gabriele Tarquini (ITA) SEAT 22:11.609

7. James Thompson (GBR) Honda 22:12.507

8. Yvan Muller (FRA) SEAT 22:13.346

9. Robert Huff (GBR) Chevrolet 22:13.611

10. Rickard Rydell (SWE) SEAT 22:15.342