Elfyn Evans admits he was shocked at the intensity of stepping up to a full World Rally Championship campaign.
The Welshman made his full-time factory debut with M-Sport on last week's series opener in Monte Carlo.
While the 24-year-old finished an excellent sixth overall, he said he was astonished by how difficult the event had been.
"Everything is so intense at this level," Evans said.
"I thought I had an idea of what it would be like, but it's definitely going up again.
"I knew it would be tough, but it just demands so much - you just never stop thinking about it.
"That's because there is so much to think about with the weather, the tyres, the set-up, everything.
"All of the time - in service, in the car, in the hotel room - you are thinking about this event.
"I would say it's the hardest event I've ever done."
M-Sport team principal Malcolm Wilson was delighted with his new driver's first outing.
"He's been great, completely calm and methodical approach, nothing has fazed him at all," he said of Evans's Monte Carlo run.
"It's been a really strong start and one that he should take a lot of confidence from."