New Zealand's Indycar champion Scott Dixon has slipped to second in the drivers' standings after finishing third at the Texas speedway in Fort Worth.
Ryan Briscoe had led for 160 of the race's 175 laps before Helio Castroneves squeezed ahead at the last pitstop.
The Australian Briscoe's now three points ahead of Dixon, who says the Target cars were flat out out all through the race trying to keep up with Team Penkse's.
He says he got caught up a bit of lap traffic in the last 10 or 15 laps and wants to see some changes to improve racing.
Dixon says it used to be possible to race side by side round the outside of the banked circuit but now cars are almost identical and the rules need to change.