Mercedes look likely to face official complaints from their Formula 1 rivals over their "extreme interpretation" of the new rules around car design.
The Silver Arrows presented the design of their W13 last month, ahead of a three-day shakedown session in Barcelona.
However, reports emerged on Wednesday that, since then, some promising simulator runs have led to a radical new design featuring changes to the car's sidepods.
And those reports were proven to be correct as it took to the track for the first day of pre-season testing in Bahrain on Thursday morning.
Sky Sports pundit Martin Brundle likened the car design to a melted bar of chocolate, with the sidepods seemingly non-existent in their new design.
Rules are there to be interpreted, and F1 is no stranger to some quite radical designs.
The sport's managing director Ross Brawn knows all about that, having been the chief of the team named after him which stormed to the 2009 title with its double diffuser.
He got his first in-person look as he took a stroll with the Sky Sports broadcasting team along the pitlane on Thursday morning, and gave his opinion on the new design.
"There is no doubt that the Mercedes concept is something we didn't anticipate," Brawn said.
"It's a very extreme interpretation of the regulations and inevitably there is going to be a lot of debate.
"It's impressive. I think this is the great thing about the innovation in Formula 1.
"It's just keeping them within boundaries which are sensible and there are no compromises in terms of the objectives that we wanted to achieve.
"I think you have to be fair. When a team comes up with an idea with innovation, with novelty, you shouldn't penalise it straight away.
"But I think, as it's understood more, and the FIA really as the regulators will know everything that's going on there.
"We don't as Formula 1 because we're not entitled to have that information, but the regulators will know everything that's going on.
"I think they're okay with it so far but of course a team may come in and raise an objection that the FIA have to consider and then you have a problem.
"I've been through that many times where your idea is okay, the FIA agree its okay and a team comes in with a perspective that has never been considered and have an argument that's valid.
"I'm sure there's going to be a lot of discussion about it but it's impressive. For a set of rules which everybody said were too prescriptive, we're seeing all these solutions."
