Marc Marquez's left shoulder was so damaged that it fell out of the socket as soon as he received anaesthetic during December's operation.
That was when doctors realised they had a much bigger than expected problem on their hands, to cure the reigning five-time MotoGP champion's dislocation issues.
Surgery time was tripled to four hours as a result, with a long and painful rehabilitation to follow. Yet the Repsol Honda star was back on track, and back at the top of the timesheets, during the opening day of 2019 testing at Sepang.
"To start this season without an operation would mean in every crash I would [dislocate] the shoulder," Marquez said.
"To see how much it was at the limit, when I went for the operation, they put the mask on me, I started to sleep and the shoulder came out on its own.
"That's when the doctors started to be scared and for that reason the surgery was much more aggressive than they wanted.
"When they opened the shoulder, they saw that there were many tendons destroyed. So then they did two different surgeries in one.
"The plan was that the operation would be more or less one and a half hours. In the end, it was four hours inside the operating theatre. So for that reason, it is taking more time [to recover]."
But Marquez said that just being back out on his MotoGP bike had been a massive lift.
"There were no holidays for me this winter [due to the rehabilitation work]. But honestly speaking, today riding the bike is like having two weeks holiday.
"I have another spirit, it's like another kind of adrenaline in my body."
But Marquez is still far from fully fit and had to adapt his riding position and style to compensate.
"In the first two laps, I said, 'I cannot ride'. But then step-by-step I started to try different positions on the bike, I started to change the riding style. To be fast for one or two laps is not a problem, but to make for example a long run now, it would be impossible," he said.
"I'm happy to be back on the bike. But honestly speaking, I expected to be better than I am. I am struggling more in the change of direction from left to right, especially from Turn 5 to 6, and from Turn 12 to 13, and then the brake points of Turn 9 and Turn 12.
"Rins was behind me and I'm sure he saw immediately that I'm braking much earlier!" Marquez added. "Turn 9 is where I feel worst and I need to brake very, very early.
"But luckily it's only the left corners. On the right corners, I feel completely like normal, like I can use my normal riding style. But we did only 30 laps, because already in those laps, the power in the muscles stated to go down."
Nonetheless, despite braking early in those areas and calling a halt to testing with one hour still to go, Marquez finished fastest of all on Wednesday by 0.259s from Suzuki's Alex Rins.
Aiding Marquez is that this year's Honda already has a good base.
"Even when we tried the new bike in Valencia and Jerez, we were already on the same level or slightly better than the previous one. Similar feeling like last year, but this year we also did another step.
"At the moment there are still a lot of jobs to do, because we have some problems. But now we start with a good base and this is the most important thing because I will not be able to do a lot of laps and try all the items.
"We will the most important things and then during the Qatar test or during the season we will try the other things."
Marquez said he is fit enough to accurately evaluate the new parts, but needs to be careful in areas where he is not riding as normal due to his shoulder.
"Especially I understand a lot the engine area and acceleration. Everything. The only thing is that on the entry to the corner I'm not riding with my normal riding style. So that is where I need to be careful not to miss the way," he explained.
"Because maybe now I try some things that are working well, but then when I come back to my normal riding style it will not work. So I need to pay attention there, but all the rest of the track I can ride in a normal way."
The #93 and temporary team-mate Stefan Bradl both had one plain black prototype bike available today, alongside their Repsol-liveried machines.
"It's not only one difference, it's a mix, but they try to bring here another step for the engine," Marquez said. "Of course, when you say 'another step for the engine', it is try to bring more torque and try to have like more control on the gas and the engine brake also working good.
"We gain in some of those things but we lose in others. So now is time for the data guys to analyse everything. But like always when you bring a new engine, is try to have more torque.
"The main focus is the engine at the moment, like last year, because in Qatar we seal the engines and we will go with that engine during all the season. So now we concentrate more on that area, but we also have a few things on the chassis, on a different path, that we need to try."
With team-mate Jorge Lorenzo currently sidelined by a wrist injury, the work of test rider Stefan Bradl has been even more important.
"To have Bradl in the team is a very, very big help," Marquez said. "He is one of the best test riders now, or the best one because he's riding fast, he has a really precise comments, very similar to my comments.
"Now when you try something it's already something that is working. So I'm very happy with the job of the test team and Bradl. Bradl is also working with the new parts and also Cal I think these next days will work with new parts."
Bradl was ninth fastest, 0.593s from Marquez.
