As he gears up to his impromptu F1 comeback in Hungary this afternoon, Paul di Resta admits his biggest challenge could be a physical one.
The 31-year-old was drafted in by Williams at the last minute before yesterday's qualifying session to replace an unfit Felipe Massa.
While di Resta believes he has his bases covered with regard to procedures and driving, he is expected the race on the demanding twisty Hungaroring to takes its physical toll when the race gets underway.
"I'm trained, but you're tense and you need to learn to relax and let the muscles relax," explained the Williams reserve driver.
"It's like any winter, the first day you come back – you think how did I ever drive these things and find it so easy.
"Even when I had the winter off and drove a DTM car, the first day you hurt because you're hanging on, using every muscle.
"I probably had my hardest Grand Prix round here in 2012, it was hot, so I'm not expecting it to be easy."
Di Resta's learning process associated with the FW40 was obviously fast-tracked yesterday, with the team forced to use a simplified approach which will also be applied in today's race.
"Keep it simple and letting me concentrate on pushing the two pedals and turning the steering wheel," says the straight-forward di Resta.
An approach echoed by Williams tech boss Paddy Lowe.
"We'll try and do the most we can in the laps to the grid, race starts, position in the box, that sort of thing," said Lowe.
"But it's not as though Paul hasn't race, he does know the basics and he has done many seasons in Formula 1.
"So I don't think it will take him too much to just refresh himself on those particular details."
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