Japan - Red Bull's Russian Daniil Kvyat led a rainswept Japanese GP practice on Friday (Sept 25) as bad weather kept F1 guessing who would come out on top this weekend.
Mercedes' championship leader Lewis Hamilton was fifth and third fastest in the two sessions, while team mate and title rival Nico Rosberg was third and second, but times were meaningless.
Hamilton spent much of his day sheltering from the rain, completing only six laps in the morning and eight in the second session.
Mercedes to bounce back?
Hamilton, whose team's dominance mysteriously disappeared at the 2015 Singapore GP, told the BBC: "There was not much to learn. It is irrelevant what we did today, with the weekend going to be dry."
Mercedes motorsport head Toto Wolff added: "If you don't need to test any new items on the car, there is no need to take a risk in these conditions."
Eight of the 20 drivers failed to set a time in the morning session, with cars throwing up plumes of spray when they did go out on a slippery track.
Spanish rookie Carlos Sainz was fastest before lunch for Toro Rosso, despite problems with aquaplaning on a track with improved drainage after the late Jules Bianchi's tragic accident last year.
Sainz's best time of one minute 49.434 seconds compared to Kvyat's 1min48.277 in the afternoon.
It was the first time in his 14-race career that Sainz had led a session, while Renault had the rare accolade of seeing their engines top the times in both.
Vettel on pace
Kvyat was second in the morning session.
Ferrari's Sebastian Vettel, winner from pole position in Singapore last weekend for his third victory of the season, was fourth and fifth quickest in the respective sessions.
Vettel's speed in Singapore raised questions about whether Mercedes were suffering circuit-specific problems or whether Ferrari and Red Bull had managed to rein in their hitherto dominant rival.
Suzuka, a fast track with challenging corners, should be much more to Mercedes' liking but both Hamilton and Rosberg had hoped for more reassurance than they were able to get from Friday's sessions.
Financially-struggling Lotus, whose freight was delivered only on Thursday, remained locked out of their paddock hospitality - where teams and guests are catered for - due to payment problems.
Lotus reserve driver Jolyon Palmer, replacing Romain Grosjean for the session, managed only an installation lap.
Palmer later Tweeted a picture of himself 'enjoying' the team's VIP hospitality - sitting on the floor of the garage with a packet of crisps.