Pedro de la Rosa reveals he had just ten minutes to get ready for Friday's practice after a late call to replace Sauber's Sergio Perez.
Despite receiving medical clearance to race in Canada, Perez complained of feeling ill on Friday as he continues his recovery from a heavy crash in Monaco. The Mexican made the decision not to race and as a result Sauber called on de la Rosa - who raced for the team last season - to fill the gap vacated by Perez.
Such was the nature of Perez's withdrawal, de la Rosa had little time to prepare before practice.
"I was finishing lunch when Monisha Kaltenborn [Sauber CEO] showed up at McLaren and asked me, 'are you ready? It's very likely you will have to get in the car'," explained de la Rosa.
"I checked my watch and it was ten to two and I said 'but there's 10 minutes to the start of the session!'
"From then it was a crazy race to get my helmet, my overalls, my things at McLaren, sit in the car, and set up the pedals where I wanted. But we couldn't do it, and we had to go out with the pedals where they were. But you don't have to be nervous. It's an opportunity and we have to enjoy it."
The call from Sauber was not completely unexpected, with the Hinwil-based outfit having made contingency plans during the week.
"Martin Whitmarsh had told me that Sauber had called in case there was a chance, but told me not to get carried away. So I arrived here thinking it was impossible. I knew Sergio was fine and I was sure I wouldn't get in the car, until ten to two," said the Spaniard.
While eager to make the most of the opportunity, de la Rosa is not getting to carried away regarding what he can achieve.
"Let's be realistic. I have a lot to learn yet. I need a lot more discipline with the buttons, the KERS, the DRS, because I'm used to a car with the buttons on the opposite side," he said.
"So I have to look at the buttons and then push it. It doesn't came naturally yet. We'll be fine. I have to improve step by step, but I'm happy because I didn't expect it," added the 40-year-old.