Maverick Vinales says the Yamaha's deficit in power relative to the Ducatis meant he "had no chance" to defend a MotoGP Aragon Grand Prix podium late on.
Vinales made his way up to second ahead of Pramac Ducati's Jack Miller in the early stages of the 23-lap race, and at one stage was able to put a second between himself and the chasing pack.
But Vinales lost grip in the closing laps and was reeled in by works Ducati rider Andrea Dovizioso before Miller snatched the final podium spot away from him at the start of the final lap.
Dovizioso had a near-5mph speed advantage over Vinales on the 900m back straight to help make the overtake, with Vinales insisting Miller would have made the same move had he not passed the Yamaha at Turn 1.
"I had no chance [against the Ducatis on the straight]," said Vinales when asked how important it for Yamaha to find more engine power.
"Even if I was able to keep Jack behind [on the last lap], he was able to overtake me on the straight.
"So I got no chance to fight with Jack or Dovi. I tried my best as always, I think we did a good race.
"Last year here it was a disaster (Vinales was 22.457s off the win in 10th), and this year we were close to second.
"As I said, we need to keep working, it's important to understand the way to go."
Vinales tried the new exhaust that was debuted in the Misano test during practice and Yamaha team-mate Rossi recently praised the M1's updated electronics, as well as recently-introduced parts like a carbon swingarm.
"It's true with the new parts I gained quite a lot of speed, because in FP4 I was fifth in [the] top speed [charts]," said Vinales.
"So, I gained a little bit more, but we lost in other places. So, still, we need to understand how to work with [the new parts]."
Earlier in the Aragon weekend, Rossi - who was eighth in the race - labelled the M1's acceleration "less embarrassing" than one year ago.
But Vinales urged Yamaha to now find more power relative to Ducati and Honda, as he believes they are gaining three tenths in lap time for "free" on straights in comparison to Yamaha.
"For sure we need to improve because Honda and Ducati, they are a step ahead," he added.
"So, it's always three tenths free [they are gaining on power], doing the same, and that's important over 23 laps."