Toseland has fallen away in the fight for third position in the World Superbike Championship standings after managing just a single ninth place finish at Miller Motorsports Park.
Riding the Utah circuit for the first time this weekend, Toseland's hopes were high after making a good start in free practice, but after qualifying down in 14th position, the Briton had it all to do in the races.
Still, Toseland managed good starts in both races to quickly breach the top ten, the former champion getting as high as seventh in race one before tyre problems consigned him to an eventual ninth.
However, his hopes of faring better in race two came to an end with six laps remaining when Toseland, having moved into sixth, lost the front-end of the Yamaha into Withcraft.
"A frustrating weekend for me,” he said. “We started really well here and I got down to some pretty decent times relatively quickly in the first practices so was feeling confident for the races. Superpole didn't go quite as planned so I had a less than perfect grid start position. I managed a good start in the first race and was making up places but unfortunately I ran out of grip several laps from the end which slowed me down.
“It took me a while to get into a good pace in race two, but as I was picking up I came out of one corner too fast and so was too hot into the next, resulting in losing the front end. The team have worked really hard all weekend and I'm sorry I couldn't deliver them a better result today."
Toseland has now slipped 19 points behind Jonathan Rea in the battle for third, while he is coming under increasing pressure from Troy Corser and Leon Camier for sixth.