Marc Marquez admits his opening to his rookie MotoGP campaign has exceeded all his expectations.
The 20-year-old followed up a podium on his grand prix debut with victory at Austin, in the process becoming the youngest winner in the sport's history.
He also moved into a share of the championship lead, level on points with last year's champion Jorge Lorenzo.
Asked if he had expected to meet such success so quickly, Marquez said: "If I'm honest, no. To be here and be third in the first race was already a dream; now with victory in the second race it's even better.
"I was so happy already at Qatar, but here with victory I'm even more so."
Marquez said victory had provided a further boost to his confidence, but cautioned that maintaining his form over the remainder of the season, and at tracks where others have vastly more grand prix experience, remains daunting.
"For me it's another motivation," he said of his breakthrough win. "Since I started everything has been good, but with victory your confidence changes a little bit.
"Everything looks like its going good, but think it will be so difficult to fight with these guys every race and keep this level.
"I cannot forget this is my first season, so now it will be more difficult - [racing on] some tracks where Yamaha is strong, [where] everyone has [more of] a base. Our battle is like that.
"We cannot think about the championship because [others] are strong - Jorge [Lorenzo] was struggling in the weekend but was so close in the race."
Marquez added that he suffered during the race, both physically and with his front-end set-up, and had been forced to ride at his limit as a result.
"I don't know why but in the race we had some front-end problems and were struggling quite a lot, especially at the end," he said.
"I was behind Dani [Pedrosa], tried to follow him and [once past] to open a gap, but we had some front problems and many times I was close to crashing.
"It was a little bit scary, but then Dani did a little mistake and I opened a gap.
"It wasn't so fast, but it was enough, and like that we took the win."