The Spanish driver reported feeling unwell on Wednesday in Jeddah with his condition worsening on Thursday.

Despite that, he completed the opening day of track running before being diagnosed with appendicitis on Friday morning.

As he went into surgery, Oliver Bearman became the youngest driver in Ferrari’s history to drive for the Scuderia, as he deputised for the 29-year-old.

Sainz is now gearing up to get back behind the wheel in Albert Park.

“Every day feeling a lot better,” the Spaniard said of his recovery.

“Now every 24 hours that I do, I do a lot of progress.

“It’s true that the first week was tough, a lot of time in bed and recovering. That’s when you see things a bit darker, but then in the second week the recovery speeds up a lot and I started to feel a lot better.

“Obviously, I put together a very strong recovery plan since I landed back home to be ready for this race, I will jump in the car [today], see how I feel, but I’m feeling positive about it.”

Sainz recounted how he was initially diagnosed with food poisoning before his symptoms worsened, resulting in surgery.

“At the time, it was very difficult to know it was appendicitis,” he revealed.

“On Wednesday, I started to feel really bad in the paddock, and I got the typical symptoms of food poisoning – I don’t think I need to go into details of what that is, and I got a very high fever also.

“I spent Thursday also with those symptoms but obviously with medication – when I was jumping in the car I was feeling a lot better because I was getting the medication.

“After those two sessions, I realised I cannot keep going like this for the whole weekend, so if I’m not improving I’ll go to the hospital.

“I didn’t improve in the morning of Friday, which was qualifying day, I went to the hospital and got diagnosed with appendicitis, which was not easy to diagnose,” he added.

“My analysis and the tests they were doing were not clear, so I didn’t have the typical symptoms, but they were pretty convinced.

“I got the surgery done, which was a great job from the doctors because as soon as I got it removed I felt back to normal, better, and I could start focus on recovering.”

Sainz was back in the F1 paddock on Saturday in Saudi Arabia where he watched Bearman take his place to record an eighth-place finish.

His approach in Melbourne today will be to confirm his fitness and assess his ability to complete the weekend.

“First of all, just by seeing me move and the exercises that I’m doing in the gym or anything, this tells me I’m fit to jump into the car [today] and try,” Sainz said.

“But obviously, I’m not stupid, and if I don’t feel good [in the car], I will be the first one to raise my hand and say that I need another two weeks to the next race.

“This, together with the FIA, is also the plan that we have in place. I have another check with the FIA.

“I’m the first one that doesn’t want to be in pain or to suffer, to make it any worse. I’m not stupid, and I will be very clear with how I’m feeling and everything.

“On top of that, just going back to Thursday [in Jeddah], I wouldn’t have jumped in the car if it wouldn’t be possible.

“I did the 26 laps because I could, not because I was in agonizing pain. Yes, it was not an easy 26 laps per session, but I could get them done.”

His ordeal mirrors, in many respects, that of Williams driver Alex Albon who missed the 2022 Italian Grand Prix due to appendicitis.

The Brit returned just a race later, at arguably the most gruelling event of the season in Singapore. However, Albon had two weeks off between events, whereas Sainz has had just one.

It’s an aggressive recovery timeline, though advancements in surgery techniques have reduced recovery times.

“When my dad had the operation 30-40 years ago, they cut you open,” Sainz said of his procedure.

“Nowadays, here with laparoscopy, they do three very little holes. That speeds up the recovery, twice or three times as fast as what it used to be.

“The doctors after the operation said it’s obviously going to be tight. It’s 14 days from the operation until I jump in the car on Friday, but possible.

“Then obviously, they don’t know what F1 is and the g-forces and everything, but possible it is, and possible I feel like it will be, given how I’m feeling now.

“Will I be at 100 percent? For sure not. It’s not a lie. 100 percent would mean spend 10 days training, doing simulator, I haven’t done that over the last 10 days, I’ve just been focused on recovering.

“But will I be fit to race? The feeling right now is yes.”