Robert Kubica is happier at the wheel of his Williams this weekend in China.

In Australia and Bahrain, the Pole - having returned to F1 after an eight year injury break - suspected that his chassis was not the same as his teammate George Russell's.

"The balance is completely different here but we are still a long way behind," Kubica told Eleven Sports in Shanghai.

"The gap to the others is still there, but we've changed a few things," he said. "We've exchanged a few things with Russell and I think the situation has reversed, but we'll see how it is for the rest of the weekend."

However, Kubica said both he and Russell are stuck at the back of the grid for now.

"If within two months we have not done anything to change the situation, it certainly will not happen in the next 12 hours," he said.