Lewis Hamilton's opening day of running in Shanghai saw the reigning world champion struggle to find the right set-up for his Mercedes W10.
While team mate Valtteri Bottas topped the timesheet in Friday's second practice session, Hamilton had to make do with a relatively subdued P4 performance, some seven tenths behind the Finn.
"It was quite cold out there, which makes it difficult for the tyres," explained Hamilton.
"I was struggling with the car today, so we've got work to do, particularly on my side as Valtteri looked much more comfortable in the car.
"We're going to work hard tonight to find some tweaks and hopefully come back stronger tomorrow; the car has the pace in it to compete at the front, we just need to find the right set-up.
"As we expected, the Ferraris still look quicker on the straights, but overall it's very close between the top cars and I anticipate that it is going to be the same tomorrow."
Despite clocking in with the fastest lap, Bottas wasn't getting carried away with his performance.
"The day ended up ok, we made it to the top of the time sheets, but it is always very difficult to find a good balance through an entire lap on this track," said the current leader of the world championship.
"We got there step by step and the car was feeling okay in the end, but it's only Friday and it's the next two days that count.
"Ferrari still seem to be quicker than us on the straights, whereas we were better in most corners in FP2.
"We still have room for improvement, but we know the others are going to work hard on their cars as well, so we're going to have to wait and how much we can improve in relation to them."
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