Since taking second place in Qatar in his first race back at Yamaha, Rossi has struggled to make an impression, with qualifying being a particular weak point.
The seven-time MotoGP champion has yet to take another podium, and is fifth in the standings, 63 points behind leader Dani Pedrosa and 56 down on team-mate Jorge Lorenzo.
He has qualified on the third row at every race bar Jerez, where he started fifth.
But set-up changes made in tests at both Barcelona and Assen this week have buoyed Rossi.
"First of all we modified a bit the setting and also the front fork and now I feel more confident in braking," said Rossi.
"I can brake deeper and stop the bike in a better way. For me this is the biggest improvement.
"After this we tried the swing arm like Jorge has it, a little bit more stiff which I like. We tried some other small things; at the end we made a good package that gives me a really good feeling, especially in braking.
"I'm so happy because until now I didn't have this feeling in braking, I am always in a bit of trouble."
Rossi is now eager to see if the gains he made at Aragon translate elsewhere. The next race takes place at Assen on the final weekend of June.
"I can't wait for Assen to understand if this is also improved at other tracks," he said.
"It is important for the qualification lap because you have to push more in braking.
"This result is especially important here in Aragon as this is not one of my best tracks. I have not made great races here yet but the pace and the lap times at the end make me very happy."
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