Toto Wolff says even a team like Williams cannot be discounted from coming up with a Mercedes-beater next year, amid fears that loopholes in the rules could be key to the Formula 1 battle.
As teams work on honing their cars to new aero regulations that are aimed at improving overtaking, Wolff maintains his belief that the order could be turned on its head by teams exploiting potential grey areas in the rules.
He thinks a repeat of 2009, when Brawn emerged from nowhere to triumph thanks to its double diffuser design, could be on the cards and that any outfit has the potential to come out on top.
"I think with the rule changes everything is possible," he said in Russia on Friday, ahead of the FIA Prize Gala.
"It is almost like 2009 where Brawn identified the double diffuser. I think there could be teams that have found loopholes, which others didn't spot, that could make the difference.
"So we are taking everybody serious: whether it is Ferrari finishing second this year or Williams finishing 10th. All of them could come with a car that can outperform us.
"We are respecting all these teams and the effort they put into it and all of them are being seen as competitors."
Although Mercedes successfully saw off the threat from Ferrari again this year, Wolff thinks that his team will face a tougher time in 2019.
"The points go back to zero at the start of every single year," he said. "The challenge is going to be bigger than it was this year.
"We're in a good mind, good spirits, that we can achieve it. But I can tell you: Ferrari and Red Bull and all the other guys will be trying everything to stop us."
Wolff revealed recently that Mercedes had suffered a minor "setback" with its 2019 engine having not delivered the step forward in performance so far that the team had hoped for.
However, Wolff is clear that Mercedes needs to set overly ambitious targets on the power front because of the growing threat from other manufacturers.
"We've seen throughout the season that all engine manufacturers including us have made big steps," he said.
"Ferrari have a very strong power unit this year. Honda made big improvements with exceptional performances in the Toro Rosso. Also Renault propelled the Red Bull to be a win candidate at almost every race at the end of the season.
"You can see engine performance is converging. We have been the leader of the pack for many years now and, in order to stay leader of the pack next year again, and return to this position, we need to push very hard and we need to set ambitious targets.
"But as Formula 1 has also become an efficiency formula, it is important you need to have the most powerful engine that actually finishes the race. It's not only about peak performance, it's about peak reliability. That balance is very difficult."
(L to R): James Allison, Mercedes AMG F1 Technical Director and Toto Wolff, Mercedes AMG F1 Director of Motorsport
Photo by: Jerry Andre / Sutton Images