After suffering the first two win-less seasons of his premier class career with Ducati, his switch back to Yamaha produced an instant jump up the timesheets at Sepang in early February.
Rossi said he felt revitalised by his return to the top of the timesheets.
"I'm relieved [and] very happy with the way the first test [went]," he told Motosprint.
"I said I wanted to understand if I'm still a top rider. I had my own doubts too.
"I'm there already, with the strongest riders in the world, the ones at the top of their careers.
"I feel I'm born again. I'm not far off."
The 33-year-old admitted however that he no longer enjoyed an advantage over the rest of the field in terms of race preparation and strategy.
"The race, side-by-side fighting, has always been one of my strong points. Unfortunately however, due to the way MotoGP has gone, this is less and less important compared to some time ago," he explained.
"There is almost no more strategy involved, but just pure speed. [Previously] you could win races despite being perhaps a bit slower than your rival: there was more room to invent something.
"Let's say that it's an advantage I used to have in the past that has become a lot less important now.
"I've [also] taught a lot to the riders who have come after me [to] take care of every detail in order to arrive at the race in the best possible condition.
"So, the end result is that I don't even have that advantage anymore."
While he admitted to losing some of his past primacy, Rossi insisted that he had surrendered none of his pace or bravado through age.
Asked whether entering his 30s had dimmed any of his faculties, he replied: "I read somewhere that 'experience' is the name one gives to his own errors. It's a nice sentence, and it's very true.
"You don't lose much in terms of not being aggressive, or not being able to ride at the limit anymore because of fear.
"You try to risk a bit less at difficult times, for example when it starts to rain and you're on slicks. Here the recklessness of a youngster who has never crashed seriously offers an advantage.
"Having gone through that and crashed in those conditions, perhaps only unconsciously I remember that and my brain tells me to be careful.
"Maybe that's what you lose but, as for the rest, in my opinion I've lost nothing."