Japanese GP: Mercedes' Hamilton and Rosberg surprised by dominance

The world championship rivals topped one session apiece as they dominated the first day of Suzuka practice, with only Ferrari's Fernando Alonso getting within one second of the pace in the morning session.

When asked if he was surprised by the gap to the rest of the field, Hamilton said: "Yeah. It changes from track to track and I don't really understand it.

"It's amazing what this team has done, to be able to come to one of the most demanding circuits for downforce and be that competitive is fantastic.

"The car didn't feel spectacular this morning, but on the option [tyre] it felt really good."

Rosberg added: "It's good everywhere - one lap, long run, everything.

"The team has really brought a great car here. It's great to see. I think this track suits us.

"Yes I am a bit surprised [by the advantage] but the car just feels good.

"I feel comfortable out there and it's great to drive. All in all positive."

Red Bull's Daniel Ricciardo, the only non-Mercedes driver to win a race this year, said he was not expecting Hamilton and Rosberg to be so far clear of the rest.

"I was expecting something like Singapore, being a few tenths off the Mercedes," he said after the session.

"They were really quick today. We think they are there and then they pull out a gap like this.

"Looking at today we are not going to be able to do anything with that in qualifying.

"Maybe the race will change, but in the dry we could still be third on the grid."