Saturday at Sepang saw Marc Marquez ride his first MotoGP laps since winning the Emilia Romagna Grand Prix on October 24.

An enduro accident and nightmare repeat of nerve damage to his right eye then forced the eight-time world champion to end the season just as it had started; missing two races due to injury.

The Repsol Honda rider's Malaysian return was on a very different RC213V, radically re-designed to try and get back on technical terms with the likes of Ducati, which dominated the closing rounds of last season.

Marquez finished the opening day in eighth place, but most importantly emerged from two falls (Turn 9 and Turn 15) without triggering further issues with his eye.

"When I spoke to my doctor, it was my first question: If I crash in the Malaysia test, what is the possibility to create the same problem again?" Marquez said.

"And the answer was clear: the possibility is the same that you will have in two years. The nerve problem is there. If you crash tomorrow or you crash in two years and you touch that nerve again, it will be damaged."

It had been a Moto2 fall at Sepang in 2011 that first revealed the 'weak point' of the nerve in Marquez's eye.

"I have strong bones because during all the crashes I only broke the humerus. But that nerve specifically, [the doctor] doesn't know why it's my weak point."

Major changes to the RC213V, which other Honda riders have characterised as providing increased rear grip, combined with Marquez's long absence from the race track contributed to today's falls.

"The bike is different," he said. "Today I had last year's bike too, and immediately I understood that the lap time is easier to get with the new bike. But this creates another problem of course, like always.

"And one of the things that I must learn and understand is that the front feeling has changed a lot. For example, one mistake today was completely my mistake, and one time I crashed and I didn't understand why. Because I didn't make anything strange.

"So all these things plus a long time without riding a MotoGP bike created [a situation] where I still don't understand well the way to ride this bike. The lap time was coming, but I don't know why.

"Still with this bike we need to understand especially the setup we have to use. Because the numbers we had in the past we have to forget."

Marquez might also have to move away from relying on corner entry to gain time; "At the moment, I need to sacrifice that a bit. Today when I tried this, I lost the front."

The #93 - who said his right arm has also improved over the winter, after inflammation issues during last season - now hopes to try some new parts tomorrow.

"Today I said to my team, 'forget trying things, I need to do laps', and we finished with the same bike that we started. So we tried a few things, but not much. Tomorrow if I feel ready, I will try."

Team-mate Pol Espargaro was a fraction behind Marquez in ninth.

"We’ve had a good first day on a new bike but the best is yet to come and hopefully we can continue to improve and show the potential tomorrow," Espargaro said. "I spent the day working on medium [tyres], not chasing a fast time as today we were trying many things. Tomorrow we’ll look for a lap time.”

Just three more days of MotoGP pre-season testing, at the new Mandalika circuit, will remain after Sunday.