Felipe Massa says that upgrades Williams has brought to the Chinese Grand Prix have improved the feeling of the FW36.
Massa was seventh quickest in the second session in China and reckons that the car has been improved.
"All of the upgrades we brought here have improved performance which is really positive," he said.
"Having new parts that we will use is good news as we have made some good steps forward. The balance and feeling of the car is better, however we know that most other teams have also made improvements.
"The low track temperatures made it slippery, and if it rains tomorrow it will be the same in the race. We also suffered some graining on the front but we can make some changes to sort this problem. Today has been a good day and the long runs gave us some good data to work on."
Team-mate Valtteri Bottas missed the first session after standing down to give Felipe Nasr some track time but the Finn reckons Williams is in a better position compared to where they were in Bahrain.
"Conditions made it hard today, but we had some really good information from the new parts," he said. "It took time for me to get used to the track this afternoon after missing this morning, made harder by the fact that there are some difficult corner combinations, but once in the rhythm it was clear we have a better package than in Bahrain."