Valentino Rossi says Yamaha's choice of engine for the 2019 MotoGP season has been "more or less decided", after the manufacturer brought just one specification to the Sepang test.
Team boss Lin Jarvis had described the Sepang test as "crucial" to Yamaha's 2019 hopes during Monday's team launch, as it marked the last realistic chance for the squad to try out different engine specifications.
However, addressing the media after Wednesday's running, Rossi and team-mate Maverick Vinales both said they had only been working with one type of engine that was picked by Yamaha prior to the test.
Rossi ended the day sixth-fastest, four tenths off the pace established by Marc Marquez. Vinales was third, a little over a tenth faster than his team-mate.
"We only have one engine because Yamaha has decided this and we are happy," said Rossi.
"The engine is more or less decided, there are not too many doubts.
"The first day was quite positive because I have a good feeling with the bike from the beginning, and that also looks like [the case] with the used tyre, that is our weak point and we are not so bad.
"We tried something today that improved the performance a little bit but we still have to work, because we are in a good way but we need a bit more."
Rossi highlighted that he and Vinales have offered similar feedback regarding the problems the YZR-M1 still has.
"In Valencia, Jerez [post-season tests] we had small things [to try], not a lot," he said.
"Here we have some bigger things and I am happy about the way - especially when we spoke together with the engineers, and also with Maverick - we are all in the same way.
"We are in agreement about the weak point of the bike."
Vinales pinpointed braking as one area that he needs to work on fro the remainder of the Sepang test.
"Honestly I'm very satisfied about how the bike works, because finally after two months it works pretty [much] the same," said Vinales, who said at Jerez last year that Yamaha already had a package capable of winning.
"Normally you come here and struggle to adapt to the bike, but I adapted quite fast and that's a good point. In Jerez, the grip was much higher than here, so that's the biggest difference.
"We need to still work a lot because in the braking area I still miss a lot, a lot of lap time, so we need to keep working on that.
"Especially when I grab the brake, I have to [apply] a lot of pressure and the bike won't stop.
"Tomorrow we're going to try a different set-up because finally today we only tried the engine, so I could not make any set-up [changes], I had the same set-up as in Jerez."