Marc Marquez and Valentino Rossi to try revised MotoGP bikes

Rossi will use a new Yamaha frame he sampled earlier this month, initially during the washed-out post-Barcelona GP test.

While that running was curtailed, the team headed to Aragon to test the following day, and Rossi will evaluate the new frame during Thursday practice.

"The plan was to try the new frame at two different tracks," Rossi said of Yamaha's original schedule.

"Trying the new stuff in Barcelona was very important, because we have the straight, back-to-back [data] from Sunday, but unfortunately it wasn't possible because the conditions were very bad.

"So we tried the new frame just in Aragon, but the feeling is good and I think that we will try it also tomorrow.

"In practice we have to understand whether it is better or not."

Marquez reverted to Honda's 2014 chassis - fitted with the '15 engine, swingarm and exhaust - during the Barcelona test.

Despite the limited running, he learned enough to adopt the set-up at Assen, with the threat of rain ruling out the prospect of comparing the two chassis in practice.

"It was good, and I will use it here," Marquez said.

"The feeling was more or less what I had last year, I was able to make more mistakes with less risk.

"With what we have this year's bike, maybe we are able to be a little faster on one lap, but during the race it's so difficult to be consistent.

"And with just one mistake, you crash. I'm trying to be more on the limit and play more with the bike."

Marquez acknowledges that beating Yamaha pair Rossi and Barcelona victor Jorge Lorenzo at Assen will be difficult, but is confident that the switch will aid his race fortunes, having last finished on the podium at Jerez in May.

"In Catalunya we crashed, but the thing is that we were closer to Yamaha riders," he said.

"Still we need to constantly work but I tried to be more consistent in the race - that's where we are struggling, especially in the second half of the race.

"I think we are on the way and we are closer to getting again that feeling, like in 2014."