Sauber mechanics worked through the night Friday, breaking a Formula One curfew, to build a new chassis for Marcus Ericsson to drive Saturday at the Italian Grand Prix.
The Swedish driver, who survived unhurt after a spectacular high-speed crash in Friday's second practice session, was passed fit to compete by the official medical delegate Dr Ian Roberts.
Ericsson lost control of his car at the chicane in the opening minutes of the session and his car spun violently before barrel-rolling to a halt.
His car's Drag Reduction System (DRS) failed to close as he braked for the first chicane just after registering a speed of 320 kph in a speed trap.
The sport's ruling body, the International Motoring Federation (FIA), said that Sauber team members were at the circuit working between 1 am and 9 am, building his car around a new chassis.
The team used one of two exceptions to the curfew rules allowed each season.
His new car was approved for use on Saturday morning after a preliminary inspection.
"The accident I had in FP2 was a big impact," said Ericsson late Friday. "Thanks to the strength of the car, I am alright.
"The team is already working hard to repair the car so that I can be back on track. I look forward to driving again."
Ericsson managed only 11 laps in the wet opening practice session on Friday morning before taking part in the dry second session.
After further overnight rain, the weather improved on Saturday ahead of opening practice and qualifying with the circuit drying out steadily under a partly-cloud sky.
Ericsson swiftly proved he has retained his confidence in his car by clocking the fastest time in the opening minutes of third practice on the rapidly-drying track.