Rosberg was under threat of losing this new engine – with the spectre of taking a future grid penalty – when a problem with the cooling system caused a contamination issue in practice at Monza.

Having fired it up in Singapore on Thursday, the team elected not to run it there, but did so in Japan for today’s wet-weather running. It features the benefits of Mercedes spending its so-called engine development tokens.

“Nico is running his [new-spec] engine, the one that was contaminated in Monza, this is its first proper run again – so we just wanted to see whether it’s in good condition,” said technical chief Paddy Lowe after FP1.

“It seems OK so far.”

Rosberg reported after FP2: “It was a positive start to that one, because we tried it all day today after what happened at Monza, and it seems to be working fine.”

Singapore issues appear over

Both Lowe and Rosberg are confident that the lack of pace at Singapore was a one-off issue, and the German was just 0.023s away from setting the fastest time of the day in FP2.

“We’ve learnt lots of things and the simplest answer is it’s not simple,” said Lowe of the Singapore struggle.

“Lots of different contributors to that, but a lot of them are about the specific nature of Singapore circuit. Actually that was our weakest circuit last year, certainly in qualifying. We’re going to learn a lot from that.”

Rosberg was upbeat about his chances in Suzuka, having finished a distant fourth last time out.

“We are confident, because the car won all those races prior to Singapore,” said Rosberg. “We still think we’re looking good and will be quick, we’re not panicking or anything.

“It will be a challenge for everyone tomorrow, as we’re only going to get an hour [in FP3] in the dry to prepare everything for qualifying and the race – that’s if it’s dry, we don’t even know that yet. It will be quite intense.”

Watch Lewis Hamilton's Suzuka track guide on the latest Inside GP preview...