Valtteri Bottas will get his turn with Williams's new front nose and wing this weekend in China.
Two weeks ago in Bahrain, it was teammate Felipe Massa who ran the new pieces, with the Brazilian admitting that the jury is out as to whether or not they are actually an improvement.
"We will again have only one new nose here, but this time it will be on the other car," Massa said.
"We have to see how it works and if it is really better, or not, as in Bahrain it was hard to evaluate it. At the moment I am not 100% sure."
Asked why there is still only one new nose available, Massa said the next version is "in production".