Paul Hembery insists Pirelli is ready for the rain in Canada.
Weather forecasters are predicting very likely rain for Sunday's Grand Prix, which will be the first wet race tackled by F1's new tyre supplier.
"We've done five or six test days in the wet," insisted motor sport director Hembery to Auto Motor und Sport, "and then we had a rainy practice in Turkey.
But that is more than some drivers are saying. "I've never driven with Pirelli in the rain," revealed Jenson Button. "In Turkey I decided not to go out because we wanted to save the tyres in case it was wet all weekend."
Added his teammate Lewis Hamilton: "I did a few laps at the Barcelona test", while McLaren team boss Martin Whitmarsh admitted rain on Sunday will be a "journey into the unknown".
Meanwhile, it has emerged that McLaren's higher downforce than some key rivals on Saturday was not necessarily a clever gamble on the prospect of wet weather.
We've done five or six test days in the wet
Auto Motor und Sport reveals that the team simply didn't prioritise much time developing a Canada-specific low downforce rear wing.
"When I look at the lap time (in qualifying) it was perhaps a mistake," admitted Whitmarsh.
In the meantime, all eyes are on the skies as many drivers contemplate their first real action on the Pirelli wets.
"What will be important will be coming around the circuit without making mistakes," said Virgin driver Timo Glock.