Ben Spies will take a 15 point advantage over Noriyuki Haga into the final race of the 2009 World Superbike Championship after cruising to victory at Portimao, while his title rival crashed out of contention.

Spies fended off the attentions of Max Biaggi and Jonathan Rea to take a comfortable lights-to-flag victory, the American completing the first half of his objective to secure the double he originally needed to guarantee himself the title.

However, it is now just a top six finish he requires in the final race of the season to ensure he wins the trophy in his maiden season after Haga threw away his advantage with a fall on the seventh lap.

The Japanese rider was up to fifth position when he lost the front-end of his Ducati Xerox at turn four, forcing him into retirement.

Indeed, the erstwhile championship leader had been making solid progress up the order from his tenth place starting position, Haga getting a decent getaway to survive the melee into the opening bend and rise up to eighth place immediately.

Spies, however, had executed the start he needed to get out in front, the Yamaha man plunging into the opening turn ahead of Biaggi, Shane Byrne, Rea and Leon Haslam.

With Michel Fabrizio's poor start effectively ruling him out of victory contention, he quickly dropped behind Haga and shadowed him as his team-mate battled it out with fellow Ducati rider Fonsi Nieto.

However, far from bowing to expected team orders, Nieto put up a staunch defence of sixth position on the DFX machine, holding off Haga until the start of lap two when he was overtaken through the opening bends.

Quickly latching onto the British group of Rea, Byrne – the pair having swapped positions at the start of lap two – and Haslam, Haga had an even tougher time working his way past, but was gifted fifth when the Stiggy Honda rider ran wide at turn one whilst under pressure from the Ducati on lap six.