Sebastian Vettel admits his Ferrari car has yet to hit the "sweet spot" despite a closely fought practice ahead of the Chinese GP on Friday.

The four-time world champion was only a tenth of a second slower than pacesetter Lewis Hamilton in Shanghai, but that was enough to see the German as low as fourth on the timesheets as the top two teams were locked together.

Heading into this weekend, after making it two wins from two just five days ago in Bahrain, Vettel knew the cooler conditions and track layout was likely to better suit his rivals at Mercedes.

However, with the times so close, he knows every little bit of performance found is going to be crucial.

"I think the car has the pace but we need to make sure we get it to work," he told reporters.

"Today was mixed, in the afternoon I was a bit happier but hopefully tomorrow I am very happy."

Despite his successful start, the 30-year-old has admitted he is yet to fully get to grips with the SF71-H.

Indeed, it has been his teammate Kimi Raikkonen that has often been the faster of the two Scuderia drivers.

The main weakness has been at the front with the car not so willing to turn into the corner as Vettel would like.

"In Australia I struggled, Bahrain I was much happier but here it is not yet where I want to be," the former Red Bull driver explained.

"We are still looking. If anyone has any clever suggestions they are welcome. It is difficult to find the sweet spot but if you do then you can unleash the pace."

As for Raikkonen, the Finn was only 0.007s slower than Hamilton in second on Friday and, in typical Kimi style, was simple with his evaluation.

"We had some traffic and could go faster on one lap. On the long run we never really got a good idea of where we are with the conditions," he said.

"We will see what happens tomorrow."