Eugene Laverty took fifth and fourth places in Monday's World Superbike Championship races at the Miller circuit near Salt Lake City.
Ballyclare's Jonathan Rea crashed out on the opening lap of the first race after a tangle with Max Biaggi and then finished 11th in the second race.
Toomebridge rider Laverty won both races in the previous round on his Yamaha machine.
Series leader Carlos Checa won both of Monday's race.
Checa finished ahead of Jakub Smrz and Sylvain Guintoli in the opening race and led home Aprilia Alitalia duo Leon Camier and Max Biaggi in race two.
In the championship standings, Checa leads with 195 points, from Max Melandri on 134, Max Biaggi on 133 and Laverty on 109.