Valtteri Bottas and Lewis Hamilton reflected on an excellent day at Suzuka as Mercedes closed in on a sixth consecutive constructors' title.

The duo secured a one-two in both free practice sessions on Friday as the iconic circuit braced itself for the arrival of Typhoon Hagibis, which has led to qualifying being put back to Sunday.

It remains a possibility that qualifying could be cancelled, which would mean the results from practice determine the grid for the Japanese Grand Prix.

READ : Typhoon-hit Japan GP qualifying moved to Sunday

And, with Mercedes needing to beat closest rivals Ferrari by 14 points in order to seal yet another constructors' crown, Bottas and Hamilton were in buoyant mood.

"Very positive day," said Bottas, who sits second in the drivers' standings, 73 points behind Hamilton.

"We tried the new bits in the car we had for this weekend. Glad the weather stayed good, so we got plenty of running and used, obviously, some tyres from Saturday as well.

"Good running, felt good since the beginning, pretty happy with the car in general. Just a few minor things with the balance to tweak, but both short and long runs at least felt good.

"It's always so much fun here driving these cars, very enjoyable, and especially when the car feels good, it's even more."

That was a sentiment shared by defending champion Hamilton, who is firmly on track for a sixth world title and has won four of the past five races in Japan. 

"It's still pretty amazing driving this track," he said.

"We've had the right tail wind into turn one, which means a head wind through the first sector, which has been great, and we've got through our programme.

"Valtteri had a little spin on one of our laps that we were about to start, both of us. But nonetheless it's been a good day, Valtteri showed good pace. It's quick for us at the moment."