Felipe Massa has revealed that a shortage in spare parts kept Williams locked in their garage in FP2 for the Australian Grand Prix.
As the rain came down at the Albert Park circuit many teams opted for minimal running but still stayed out long enough to set a lap time.
Both the Brazilian and his team-mate Valtteri Bottas failed to set a time in the afternoon's session with both drivers covering just two laps.
"We're quite short on parts, that's why we didn't run," Massa explained to Autosport.
"We saw other teams not running as well, so maybe they had similar issues to us."
Massa reckons Williams were vindicated in their decision not to run when Nico Rosberg smacked the wall in FP2, destroying one of Mercedes' front wings.
"That's why we decided to stay in the garage because if you crash it would be very tricky for us looking at the parts we have for the car to get the best out of the weekend," he said.