Riding at a circuit where Espargaro and the previous RS-GP endured a nightmare weekend last October, Vinales was competitive throughout Friday, eventually finishing with the seventh fastest lap time (+0.543s).
"After what Aprilia achieved in Argentina, we can’t relax," Vinales said. "We need to keep the same mentality. Same focus. And keep working. The way to build a consistent bike is to be pushing at the maximum every day.
"We are doing little steps but always going forward. I’m very happy about how things are going."
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After struggling to feel comfortable on the Aprilia in Qatar and much of the following Mandalika weekend, Vinales is now all but certain that a set-up breakthrough was indeed made during warm-up in Indonesia.
"The main point of today is we confirmed once again that the move we did in warm-up in Indonesia is good," Vinales said. "Different tracks, layouts, rear tyres… and it’s working.
"We can say that we’ve found a base set-up and from here we can only improve.
"I’m very happy about today. I had the same feeling than Argentina. It’s just that here, I’m a bit better [as a rider here] than Argentina. Maybe the characteristic of the track.
"Our race pace is very promising. Tomorrow I have to concentrate very well on one lap because qualifying is such an important moment. We have to be ready.
"But we don’t want to rush too much. We know the potential, we know our level. It will take time to be faster. It’s a matter of keeping working, and understanding the bike. Every time I go on this bike, I feel better. This is a good sign."
'I'm not good here!' - why Aleix Espargaro is happy with 11th
New world championship leader Espargaro may only have managed eleventh but he was also all smiles at the end of day one, given his previous COTA struggles.
"After the win in Argentina, finishing eleventh here I would never say I would be happy - but I am because last year I suffered a lot," he said. "I finished 20th every session, I crashed a lot. But I feel very strong, very fast from the beginning.
"It's true that I wasn't fast enough on the soft tyre. With the soft sincerely I didn't have a good feeling. But with the medium tyre I was very strong. Many laps in 0'3s high which is good. I think I've been one of the fastest with the medium tyre.
"So tomorrow morning just need to push a little bit more with the soft to be inside the top ten. But it has been a good Friday. I am very satisfied. The Aprilia this year works much, much better."
Asked where the 2022 bike is better at COTA, Espargaro joked: "Even in the pit garage! Everywhere. It's another story. But it's not fair really to compare because I think I'm a little bit faster, the bike is a lot different than last year and we have new tarmac.
"But last year I remember many sessions struggling to go under 2m 0'6. Crashing a lot, a lot. Just one lap I think all weekend under 0'5! And this year I was able with the medium tyre to put many laps in the 0'3 high. Alone. With good pace. Making no mistakes. So I'm very happy.
"It's not just the bike, it's also me, I'm not super good here," Espargaro added.
"There are a lot of corners in first gear that you have to stop completely the bike and I'm not competitive managing these type of corners. Also I like to accelerate normally and keep turning and in this track you have to pick up the bike quickly.
"This is why I'm very happy to be this competitive on day one in America."
Top six at worst track?
"I'm sure that I will be able to fight for the top six," Espargaro predicted for Sunday. "Which in the worst track for us of the season, for Aprilia and also for me, would be fantastic.
"I'm very focussed, sincerely. Very concentrated. Trying to analyse every single thing that I can improve with Matteo [Baiocco], who is on track seeing the other bikes, and also with our cameramen trying to compare the videos. Also analysing Maverick's data because he is very strong here in America, which he proved today, he was two tenths quicker than me.
"So I will try everything I can to improve a little bit everywhere, to score maximum points possible on Sunday."
'Work together until we fight for the championship'
Rather than feeling threatened by a faster team-mate, Espargaro insisted its essential for the development of the project.
"It's always good to have a strong partner. In my years in Aprilia, I always tried to help my team-mates to be close because until the moment that we fight for the championship victory I think it's better to push two riders together to develop the bike, than one alone," Espargaro said.
"I have a good team-mate, he's fast, also we have good relations, we can talk, we are open, this is very good. I won in Argentina but believe me I'm very humble because I know that he will be very strong here.
"So I analyse a lot his data, for sure he did [with mine] in the previous races so I'm doing the same now, trying to improve as much as I can. I will ask him some tips if I need it because it's just race four so we have to try to score maximum points possible.
"I checked after Argentina where Aprilia was in the championship standings but also Maverick checked and he's very happy to see that we have many, many points for the championship. So we are a good team.
"And this American circuit for Maverick is I think one of his favourites, it's one of my worst, so I will try to use him as much as I can! Let's see if we can be together in the race."
Vinales: 'Aleix won't be far away'
"I don’t think Aleix will be far," Vinales said of his team-mate. "He will be there, fighting for the front row, second row, and also in the race because the bike is working quite well.
"It is very important to have good relations. It makes the team better. With Aleix we work pretty hard together. All the team is in harmony which is nice to see. This is the way to improve."
Seventh place for Vinales in Argentina was his best result yet on the RS-GP.