Williams have delayed their start to pre-season testing until Tuesday as their 2019 car is not yet ready.
The team had been due to take to the track in Barcelona on Monday, along with the rest of the grid.
However, having already cancelled a filming day over the weekend, Williams confirmed on Sunday that the FW42 is not yet ready for action.
"Unfortunately, we have had to delay the start of our pre-season Barcelona test to Tuesday morning," said deputy team principal Claire Williams.
"We have had an incredibly busy winter at Grove getting the FW42 prepared for the season ahead and, despite everyone’s best efforts, we need some more time before it will be ready to run.
Rocking those new driver overalls! pic.twitter.com/APVyGTQhvo
— ROKiT WILLIAMS RACING (@WilliamsRacing) February 16, 2019
"Our absolute priority is to always ensure we bring a car to the track that is the best that it can be and sometimes that takes longer than you’d anticipate or like. It’s clearly not ideal, but equally it’s not the end of the world.
"We will obviously have our work cut out to recover the time lost but we still have seven days of testing left and we will be maximising that time to prepare the car for the first race."
Williams endured a torrid campaign in 2018, scoring only seven points in the constructors' championship.
Only the former Force India team, whose points were voided after the Racing Point takeover, finished below them in the standings.
