Ruben Xaus decided not to race in the 2010 World Superbike season opener after his collision with Noriyuki Haga in warm-up left him feeling disorientated.

The Spaniard had endured a troublesome weekend up to that point, completing just ten laps during free practice on Friday after three falls left him with no spare bike to ride.

However, it was Xaus' fourth and final fall during warm-up that would rule him out of the races, the Spaniard clipping the back of Haga's Ducati at the fearsomely fast turn one to send both riders somersaulting off the track.

Although neither rider was seriously hurt, with Haga going on to claim a podium in race one just three hours later, Xaus said he felt disorientated and, after consultation with doctors and his BMW team management, was advised not to compete.

However, his team-mate Troy Corser did suggest a lack of confidence was also a factor in Xaus' decision.

"I feel sorry for Ruben today, because he has lost some of his confidence with all the crashes he had," the Australian said. "He had a heavy fall in the morning warm-up today and it was decided that he sat out the races. I think this was the right decision and I hope he will be back and fighting fit for the next round."

Xaus will return to competition in a month's time at Portimao.