Valentino Rossi completed his first laps with a prototype of the 2020 M1 during Monday's official post-race test at Brno.

With Yamaha playing catch-up to its leading MotoGP rivals, Rossi was pleased to get an August debut on next year's machine "like in the good old days".

However, the Italian also emphasised that it's very much a first version and, at present, not much has changed over the current machine.

"It was a good day, a good test," said Rossi, who set the sixth fastest lap time (+0.399s) after finishing sixth in the race. "We tried also the prototype of the new bike, but sincerely we don’t have a lot new

"It's a different engine and a little bit different setting of the chassis. But it's just the first touch and we can have something else also in the next test.

"It's already good that we have [the new bike here] but after we worked more with the standard bike."

The main difference for the new carbon-black bike at this stage is a revised engine, with Yamaha lacking clear straight-line performance against the likes of Ducati and Honda.

But again, for now there is not a big change.

"We don’t feel a lot of difference, no," Rossi said of the engine. "But we expect because it's just a little bit different in the engine.

"But this is not the 2020 bike. It's just the first prototype," he emphasised. "And we will work, we will try something else, but we need more for sure."

On the chassis side, "We try to have more grip, especially from the rear, so we try some different settings because for the rest the bike is the same.

"And we find something better, something worse, we fight a little bit with the wheelie. So we have a lot of work to do still.

"But it is just the first touch, we have a lot to do and I think that the Misano test, after Silverstone, will be important for everybody because we will have something else. But anyway it was a positive day."

Rossi, seeking to end a win drought of over two years, also tried a revised seat unit and new fairing on his standard bike.

"It is the first prototype for next year, to try like always for less wheelie," he said of the fairing.

Engine design cannot be changed during the season, while Yamaha has already used it's one available 2019 fairing upgrade.

Team-mate Maverick Vinales also had a brief run on the new bike on his way to the second-fastest lap time behind rookie Fabio Quartararo, whose team-mate Franco Morbidelli completed an all-Yamaha top three at the test.

The Austrian Grand Prix at the Red Bull Ring, renowned for hard braking and acceleration, starts on Friday.