Ruled out of the Valencia MotoGP season finale by a huge Saturday practice highside, a sore Pol Espargaro made his return to action at the start of the Jerez test.

With team-mate Marc Marquez absent due to double vision problems, Espargaro presence is especially important for HRC as it continues work on the radically revised 2022 prototype.

While two of those bikes were on track in the hands of LCR riders Takaaki Nakagami and Alex Marquez, the Japanese finishing the day fastest, Espargaro got back up to speed on the 2021 machine.

"I'm pretty satisfied I could ride 45 laps today. Honestly speaking, I feel destroyed!" Espargaro said. "Not only the pain, also riding I feel a little bit of pain, but after being five days on the sofa just recovering to come here, for sure I didn't train through those five days.

"I'm tired from the injuries but I'm also tired by myself just from riding the bike, and also the wind today was pretty strong, so this was making my life a little bit harder.

"So today I set up the current bike, and tomorrow is the time for me with the [2022] bike that has been tested by the two satellite riders, Taka and Alex."

Espargaro, suffering rib pain every time he breathes as a result of the Valencia accident, added: "I cannot jump straight onto the prototype bike without knowing how perfectly the [2021] bike works, especially in my physical condition. So tomorrow the idea is going to be much clearer.

"There are two prototype bikes, which have different things on them," he revealed. "The base is very similar, but there are different ways of getting the time. So today I think Alex was trying one and Taka another one, and then they swapped.

"I didn't talk to them yet, but I talked to technicians which have been around, and it looks like it's working, Taka is first… Just to put the bike on the track and to be already first, even if Taka is really fast here, it's something that's nice to see."

Espargaro explained that the main area of difference with the 2022 model, which he previously tried at the Misano test, is rear grip.

"For sure the Misano test was important, because we reconfirmed that what they were working on was good, so what we have here is based on what we did in Misano, it's an evolution.

"Different setups, different stuff that we can add, like different wings, different aerodynamic package, that can make the bike a little bit better.

"I think we need to generate more safety on the bike, especially on the rear tyre," he said. "This means to have the rear tyre more attached to the ground. Not just on the acceleration, to avoid the kind of highside like I had in Valencia, but also the floating feeling we have on the corner entry, that doesn't allow us to turn as fast as we would like. And for sure, to accelerate better. To use more the tyres to get more temperature in the rear tyre, which we struggle with.

"So we are trying to base the new bikes on this area, to get more rear grip, more rear contact. For sure this is going to bring different problems on the bike, some contrasts. But if we get more contact on the rear, sure the biggest crashes and the biggest problems we are having now are going to disappear.

"Stefan [Brad, test rider] has been trying the prototype. Sure we are gaining more contact on the rear. What we have been looking for, we are getting it.

"This is good from Honda. The experience they have is amazing. They know how to push the correct button when they need to, and this is nice."