Fresh from his first podium of the season on Sunday, Franco Morbidelli returned to the Jerez circuit for an 'interesting' day of official MotoGP testing on Monday.

As the only rider on the older A-Spec Yamaha, not all developments made for the Factory bikes can be fitted to his machine, due to the engine freeze rules or design changes.

Nonetheless, Morbidelli received the same new carbon fibre swingarm and front fender to try at the test as team-mate Valentino Rossi.

However, the reigning title runner-up spent the bulk of his 67 laps trying to improve his braking performance, including the use of some new front fork settings.

Morbidelli finished the day with the ninth fastest time, 0.748s behind Monster Yamaha Maverick Vinales, who also dedicated much of the day to braking.

"Interesting test. I'm happy overall," Morbidelli began. "We tried one new item and a different swingarm.

"Then we focused basically and mainly all day on the braking area and we tried some settings that gave me the chance to brake a bit deeper than usual, and have a little bit better feeling in braking generally.

"I hope that these things will work as well in Le Mans. But we've got to take it easy, because Monday tests can always be 'dangerous'. Sometimes they can take you on the wrong path.

"So we've got to reconfirm in Le Mans, but at least the things that we tried were good, because it can happen sometimes that the things you try are not good at all, so this is positive.

"But it needs to be reconfirmed in Le Mans because after the race there is a lot of rubber on the track, and then during the test day, just MotoGP bikes riding around leaves a lot of rubber on the ground, so it's because of that."

Returning to the new parts, Morbidelli clarified that the swingarm was a carbon-fibre design, while the other data-gathering task had been for the revised fender.

"Yes, we tried a new front mudguard, I don't know in detail, but it's supposed to make the bike work better. And my job consisted of making some laps and just collecting data," he said.

While the Factory-spec riders seem to be switching between aluminium and carbon fibre swingarms, Morbidelli has long preferred a composite version.

"We tried another carbon swingarm, because I already use the carbon swingarm," he confirmed. "We tried it at the end of the day, so we didn't collect too much data and we didn't work too much on it. For sure it has some potential, but we don't know if we will use it in Le Mans."

Morbidelli is currently eighth in the world championship, 33 points behind Francesco Bagnaia (Ducati).