Robert Wickens finished second with Will Power third and Newgarden fourth.
"It is what we needed," Rossi said. "We said coming into this weekend we had to execute for five weekends in a row and this is a start of that.
"Great fuel milage from Honda, great tyre life too."
Dixon was a bit disappointed with his result after such a great opening stint. He admitted they didn't quite know whether to race hard and go with three stops or save fuel and try for two.
"We were kind of in no-man's land between going with three or going for two (stops)," he said.
"It was just one of those days where we would pit for track position and come out behind somebody.
"Unfortunately we didn't get the result we wanted but it was OK."