Mercedes can still win both Formula 1 titles in 2021 but can no longer simply spend their way back in front, according to Ross Brawn.

While Mercedes' domination since 2014 has been thanks to a superior car, they have achieved that by spending more than any other team, revealing a total budget of just under £325m for last year back in May.

Now though, the Brackley-based team's seven-year record run of success is facing its biggest threat so far, with Max Verstappen and Red Bull comfortably leading both championships after the first nine races.

"This year is unusual in that the teams can’t respond in a normal way for several reasons," Brawn said after the Austrian GP.

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"One is that we have the ($145m) cost cap now, so they can’t just throw resources at the problem.

"Secondly, we have the new car coming in next year, which they will be pretty committed to, so it’s a bit of a dilemma for the team as they probably can’t afford to deliver a very strong response in the way they normally would do.

"Before the cost cap, you would throw resources at it. These are the elements of the rule changes that have been made, which are significant and slightly unseen and I think will lead to stronger championships in the future."

Mercedes has admitted an upgrade coming for the British Grand Prix is set to be the last for this year's car due to the resource focus on 2022.

And while that might appear to make Mercedes overhauling Red Bull even less likely, Brawn isn't ruling out his former team.

“Right now, things aren’t going well for Lewis [Hamilton] but he’s been through this before, albeit it maybe not for some time,” he conceded.

"This is the fascinating thing about F1. It did feel at the beginning of the year that Red Bull fumbled a bit, but now they are back up to speed and what looked to be the better car is now showing it in the results.

"At the beginning of the year, Mercedes outraced them but that is not the case now. It’s been the opposite in the last couple of races because Mercedes are trying too hard, and they’ve stumbled a bit.

“The title is still reachable for Hamilton and Mercedes," Brawn stated. "These races [in Austria] have been pretty much dominated by Red Bull, but I will be amazed if that continues at every track.”

The F1 motorsport boss also commented on Hamilton signing a new two-year deal at Mercedes until 2023, meaning the sport's most popular driver will be staying on the grid for now.

"It’s great news that Lewis’ contract has been renewed," he declared.

"He’s a Formula 1 superstar and is a key ingredient in this fantastic battle we are having for the world championship this season.

"It’s a huge positive he will be with us for a few more years and will have a chance to drive the new car next year."