With a brand new chassis, Lewis Hamilton put Friday's problems in the past as he powered to the quickest time in the final practice session before qualifying on Saturday evening.
After failing to match the pace of his teammate Heikki Kovalainen on the same street circuit 24 hours ago, the reigning world champion admitted that he simply "wasn't as fast as I'd hoped to be".
Around the same time, McLaren mechanics were discovering a problem with a cable attached to the KERS system that ran all the way through the chassis of his MP4-24.
"To fix it would have been too complicated," team boss Martin Whitmarsh told Auto Motor und Sport. "So we decided to change the entire chassis."
The situation was much more grave at Brawn, where mathematically Jenson Button could wrap up the title next weekend at Suzuka, amid reports of increasing tension with his teammate Rubens Barrichello.
At the end of Saturday practice, Button emerged angrily from the cockpit of the car having gone just 14th quickest and pleading anxiously over the radio: "What have you done to the car?"