Having tantalised fans by asking them to wait until the end of FP2 before confirming whether it was running its upgraded power unit in practice, Mercedes finally confirmed that it was shortly after the end of the second session.

In the moments before FP1, the FIA revealed that all the Mercedes-powered cars were running new ICE (internal combustion engines), turbochargers and MGU-H. However, Mercedes responded saying that it wouldn't confirm whether these components were to the new or old spec until after the second session.

In fact, speaking to Sky Sports between the sessions, Niki Lauda somewhat have the game away.

"We've been one race late with the new engine, because we really have to watch it," he said.

"It's very important that Andy Cowell is doing a perfect job," he added, referring to Mercedes engine boss.

"What I hope is that our engine will help us here to get back, because everyone improved their engine in the last race," he continued. "The difference could be one or two-tenths, nobody really knows what the others are doing.

"I just hope that our engine will work well here, this is important, so we can get pole position back."

A further clue could be found in the timesheets in the second session. Though Valtteri Bottas was sidelined for much of the ninety minutes by a water leak, Lewis Hamilton was 0.7s clear of Daniel Ricciardo who was second quickest.

While Mercedes took to social media to confirm that it was running the new-spec components in all six cars it powers, Hamilton was enthusing about the new units.

"The new engine feels clean and fresh," he said, "but we won't really know its full potential until tomorrow when everyone gets to turn their engines up.

"I'm grateful for the hard work that everyone put into it back in Brixworth," he added. "They've been pushing so hard to get this engine and do it in the right way, so a big thank you to everyone back at the factory - I hope that we can do something great with it!"

"We were running the new spec engine today which felt fresh and good, but we didn't run it yet in full power, so there's more to discover," added Bottas ominously. "We need to identify the cause of the water leak, but we're confident that we will continue to run the new engine."

Check out our Saturday gallery from Paul Ricard, here.