A tense, unwell and tired Kimi Antonelli said he will "bombard myself with melatonin" to ensure himself a full night's sleep before the Mexico City Grand Prix, where he can become Formula 1's youngest world champion.

Antonelli qualified fifth, which became fourth after Max Verstappen's grid penalty, for a race where he will guarantee himself the title with a ninth-place finish or better.

Title rivals Lewis Hamilton and George Russell locked out the front row of the grid but Antonelli's fate is still in his own hands.

Should Hamilton win Sunday's race, the fight would go on another week to Brazil if Antonelli was 10th or lower.

The 20-year-old comes into the biggest race of his life not at 100%.

He missed Thursday's media duties on Thursday due to illness.

"I feel very tired to be fair, I still haven't recovered completely," said Antonelli, who admitted he's also been distracted by the chatter about what he can achieve at this race.

"It hasn't been an easy weekend, you know, and definitely I've been a bit more tense than usual, especially, you know, when you keep hearing wherever you go, any time of the day, the same thing, and people telling that it's already done. Knowing myself, I've been trying to block as much as possible this noise, but it hasn't been easy and definitely I've been a bit more tense today."

His plan to arrive at the race championship-ready is to do whatever it takes to have a full night's sleep.

He added: "I'm going to bombard myself with melatonin, so hopefully I will sleep a good 10 hours, hopefully. Just going to try to relax as much as possible, my family has just arrived, so it's going to be good to have them here. Just going to try to disconnect as much as possible, good sleep, and then ready for tomorrow."

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Antonelli's thumping United States Grand Prix win last weekend moved him to within an inch of the title, but he arrived in Mexico under the weather.

Asked how he felt on Thursday, Antonelli said: "Very bad. I had a high fever and stomach problems, so it hasn't been easy. But now I feel OK, just low on energy, just feel pretty tired, so it's going to be important to try and sleep well, because I haven't been sleeping well in these days, and hopefully tomorrow I will have more energy."

The midweek illness meant Antonelli felt off the normal standard he's set in 2026 when qualifying started.

"I'm aware that definitely I haven't been driving well," he said. "I felt like already going to qualifying, I didn't feel great, and I felt a bit low on energy, so definitely, you know, it's not an excuse, but for sure, it hasn't been my finest performance."

Asked if he was feeling tense in Austin in the same way, he said: "No, Austin I wasn't driving tense, Austin I was much more relaxed. Definitely it's been a thing of this weekend."