Takuma Sato says his late mistake while leading IndyCar's Barber race caused a "heart attack", but described his victory as his "cleanest" in the series yet.
Sato was left without an early threat in the race after Rahal Letterman Lanigan Racing team-mate Graham Rahal encountered throttle problems.
The 2017 Indianapolis 500 winner was then able to keep fellow three-stopping rival Dixon and two-stopping Sebastien Bourdais at bay and won by 2.3s.
But Sato made a mistake while leading comfortably, launching over the Turn 8/9 chicane and skimming the gravel trap, recovering to hold a narrow advantage ahead of Dixon and Bourdais.
Sato said: "It's probably the 'cleanest' race I ever won, and again, big thank you to the team. Without their support, we wouldn't able to push this hard, and I think the engineers did a fantastic job.
"I think we came here with hopes, but I honestly never expected it to be this much of domination.
"Obviously Scott was charging hard and also Sebastien. We had about 1.5-1.8s, that sort of gap I was controlling a bit, but it's never relaxed.
"Outside it probably looked easy to win from cruising and pole position, but it wasn't really cruising.
"So I was really pushing hard using push-to-pass on every [corner] exit in the last 10 laps. It was tough, and I had a little moment into Turn 8.
"It was not necessary to give the sort of heart attack to the body!"
There were two flashpoints that could have affected Sato's race, including a long first pitstop after a left-rear wheelnut jammed.
IndyCar race control also decided to delay a full-course caution when team-mate Rahal broke down and Tony Kanaan clattered into Max Chilton at pit entrance.
Describing the pitstop, Sato said: "[At the start] we basically stretched the gap between us and the group [behind] because changing a tyre, there can be a problem.
"As a driver sitting in the cockpit and having problem...it took ages, but it's important to just [keep your] head down, and you do your job.
"You've got to believe that the boys will do an excellent job in the next pit stop, which they did.
"So perfectly OK for me. In races, it happens. I make mistakes too so I don't blame them. But I think it's important to understand what's happened and make sure we will improve for the next pit stop."
Sato added that he appreciated race director Kyle Novak's decision to delay the full-course caution.
"I think IndyCar did a great job and a great decision to obviously go to yellow because that's a safety issue," he said.
"But the car parked at the exit of Turn 9 [Rahal] was not in a dangerous position."
Get unlimited access to the world’s best motorsport journalism with Autosport Plus