Second in this morning's opening session, 0.788s adrift of pace-setter Sebastian Vettel, this afternoon Lewis Hamilton was 0.707s off the pace, this time to teammate Valtteri Bottas.

And as he spoke to reporters, it was clear the Briton is at a loss to explain where he is losing out.

"I'm just focusing on trying to figure out what the hell is going on with my car," said Hamilton, a record five-time winner at the Shanghai International Circuit.

"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," he added.

"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."

"Lewis hasn't found the car as easy to work with and we need to do some investigation overnight to understand why," admitted chief race engineer, Andrew Shovlin.

"Ferrari and Red Bull are all doing decent times on long runs and short runs," he added, "so it looks like it will be tight but we have some scope to improve things overnight. "

"We've got work to do," agreed Hamilton, particularly on my side as Valtteri looked much more comfortable in the car.

"It's nice to see how close it is between us, Red Bull and Ferrari," he added. "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."

Check out our Friday gallery from Shanghai, here.