Max Verstappen felt he was "missing a lung" after falling ill in the leadup to the Saudi Arabian Grand Prix.
The Dutchman finished second in Jeddah to maintain his early championship lead.
This came after his participation in the event had briefly been put in doubt as Red Bull confirmed reports of an illness and that he would arrive at the track a day late.
Details of Verstappen's condition were not shared across the weekend as Red Bull again dominated proceedings.
But speaking ahead of this weekend's Australian Grand Prix in Melbourne, the reigning champion revealed: "At home, I was really ill.
"I could barely just walk around and felt like I was just missing a lung.
"I got to the weekend, really believing that it was gone. Because normally when you get sick, like two, three days after you normally alright, you could just do your workouts.
"But then when I jumped in the car in FP1, even just one performance, I felt like I had to recover for two laps to be able to breathe normally.
"It definitely did affect me throughout the weekend, which I didn’t like because it was one of the first races where I felt like I was physically limited.
"That’s really frustrating when you’re out in the car but since then I’ve been trying to work on it, trying to improve it, and I do think that it has improved a lot, so this weekend should be alright."
Verstappen eager for F1 'spring break'
The Australian Grand Prix marks the end of the opening phase of the season with the cancelled Chinese event creating a three-week spring break.
“A couple of weeks ago I would say I wasn’t looking forward to it but I got really ill,” added the Red Bull driver.
“(I've) just been struggling a bit since that time, especially the last race now. So for me, those three weeks are getting back to full fitness, getting a full programme in.
“In a way it’s probably nice now but normally if you just feel well I would prefer to keep racing.”
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