Marc Marquez's withdraw from this weekend's Algarve MotoGP at Portimao was naturally one of the hot topics on the eve of the penultimate event of the season.

A short press release issued by Honda on Tuesday stated that the eight-time world champion had suffered a fall during 'one of his standard off-road training sessions' last Saturday, resulting in 'a slight head concussion'.

Still feeling unwell after a few days, Marquez was assessed by doctors on Tuesday and - that same day - withdrew from this weekend's event 'as a precautionary measure'. There were no quotes attributed to Marquez.

"It was a normal accident when you are training in the mountain with an enduro bike, or a motocross bike," team manager Alberto Puig said in Portimao. "He crashed and he had a concussion.

"It was okay but he was not feeling so good, a little bit like dizzy. So we checked with the doctor and it was correct not to race if you are not 100%.

"So we are going to wait and next Monday, Tuesday we will check with the doctor and he will make a further evaluation [for Valencia]. If the doctors says he can and Marc is feeling better then of course [Marc will be at Valencia]."

But few other details are known, except that Marquez was riding with Enduro World Champion Josep Garcia at a track near his home.

Whether the accident happened on a jump, a corner or while doing some rocky enduro single-track is unclear. Likewise, were any other riders involved or did he fall on his own? And is the 'slight concussion' the only injury?

The #93's social media simply copy-and-pasted the text from the Honda press release accompanied by a stock photo of Marquez at a MotoGP event, rather than an up-to-date image or quotes from Marquez.

"Marc? No. I was not there. I was at home. My plan was a bit different for training. I had gym and running. He went with an off-road bike on a track five minutes from my home," said younger brother and LCR Honda rider Alex Marquez.

"Unfortunately, he cannot be here and I hope he can be fit for Valencia. It’s like this. We train everyday and the risk is always there. It was a normal day, he was with Josep Garcia."

While sitting out a race weekend due to symptoms of even a 'slight' concussion is entirely sensible, some were surprised the decision was made on Tuesday rather than waiting to see how Marquez - winner of the last two races and well known for wanting to jump straight back on a bike after falling - felt on Friday morning at the circuit, after more medical checks.

"I don’t know. Nobody has information about his crash. The press release says a concussion. But we don’t know. Maybe he has a broken arm. We have no idea. We have to believe it’s a concussion," said Alex Espargaro, when asked if he would have waited until being checked by doctors in Portimao before deciding to pull out of the race weekend.

"If it’s a head concussion it must be hard. If it wasn’t like this Marc would be here racing for sure. We know him in the paddock. But it’s difficult to judge. Every injury is different. If the crash was done in the last GP we’d know the type of crash.

"Anyway, he’s not here racing. I don’t know if concussion is the right word. I think it’s something bigger."

After missing almost all of last season due to complications from a right arm fracture at Jerez 2020, Marquez returned to MotoGP action in the first Portimao event in April.

While his healing arm and shoulder is still far from 100 percent, Marquez has won three races this season, also Honda's only victories since the end of 2019.

The eight-time world champion, who has moved into contention for fourth in the world championship, had been hoping to use this weekend's race to gauge his physical improvement compared to the MotoGP comeback at the track in April.

While Marquez halted off-road riding during the early stages of his arm recovery, he returned to motocross training several months ago.