Ben Spies has completed a double victory on home ground at Miller Motorsports Park to make some headway into Noriyuki Haga's substantial World Superbike Championship lead.

Although he didn't have an interruption to contend with on this occasion, Spies was in similarly imperious form, leading from start to finish to complete his sixth win and his second double of the season.

With Haga finishing down in eighth position, to go with his ninth from the opening race, Spies has been able to reduce the chasm between himself and the championship leader by 35 points, bringing it down to a somewhat more manageable 53.

Having proven untouchable during the first race, Spies was certainly the man to beat from the start line, the Texan producing arguably his finest start of the season so far to slingshot into the lead of the race, ahead of fellow front row starter Fabrizio.

Just behind, Carlos Checa managed a good getaway from second to slot into third, ahead of Haga and Max Biaggi, the pair doing a fine job of bullying their way to the front of the field from their respective ninth and 16th place starting positions.

With clear track ahead of him, Spies quickly began asserting his authority as he pulled away from the pack, although Fabrizio was gamely hanging on as he attempted to match the Yamaha through the Utah circuit's twists and turns.

In turn pulling out a gap over those behind him, his advantage improved on lap four when third place Checa came crashing down at the Attitude chicane, bringing a frustrating end to what looked like being best weekend of the season so far.

His demise left Rea in third position, the Northern Irishman having capitalised on Biaggi's messy attempt to pass Haga for fourth, the pair losing out as the Ten Kate Honda slid through into position.

Still, while Rea could not pull away from the pack, he was able to show remarkable defensive nous against the series of rivals queuing up behind him. Haga, Biaggi and Kiyonari all tried their luck at one stage to get the better of Rea, but he was able to maintain tight lines and, significantly, get good drive out of the final corner to counteract any slipstream effect down the lengthy home straight.