Williams technical chief Paddy Lowe has revealed a key change Ross Brawn has proposed to spice up Formula 1 races.

The F1 motorsport director is currently tasked with developing new cars which will allow for closer racing in 2021 but also changes to the format are being considered to create more unpredictability.

Last year's United States Grand Prix appeared to offer a solution when a wet Friday left teams largely in the dark over tyre wear and resulted in a more eventful race with the top three drivers all using different strategies.

And Brawn has thought of a way to try and repeat that scenario at every race.

"Ross has talked about this, that you can't test any tyres on Friday, you have just a base tyre that's just to let you work with the car and learn the circuit. A few things like that," Lowe told Autosport.

"Then everything is thrown in as a lucky dip for you for the race. I think it's great."

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Right now teams can test all three compounds and often do complete a mix of long and short runs on the tyres they expect to perform best.

That means, as the former Mercedes boss explains, the element of guesswork is much less.

"The cars are completely reliable and they're completely optimised in terms of set-up, deployment around tyres or whatever, that means that the results you get are massively more predictable to the point," Lowe said.

"The major variable is the driver and mistakes he might make but even there, drivers nowadays are completely fit, so they don't even get tired like they used to, and they are well trained, coached. They don't make many mistakes, so we need to throw stuff in that stops the optimisation.

"If you want to make [the races] more valuable, you've got to prevent the optimisation and allow for effectively more disturbance, more noise, which will come from external factors, that we couldn't optimise around," he continued.

"The other alternative you get rid of the engineers by cost cap or reduce the operational staff level here [at the track]. I am not trying to just make a lot of engineers redundant, they can do other things.

"I think Ross has realised [that optimisation is causing predictable races], that's his own observation, and he has a project around that."