Mercedes has revealed engine problems led to fears of a "painful" start to last season before it was delayed by Covid-19.

When the racing commenced in July, the German manufacturer was in a league of their own with a significant power advantage, particularly in qualifying, one of the main reasons for that.

However, back in February during winter testing, reliability issues dogged Mercedes and also Williams, with the oil system being primarily blamed for the stoppages.

And though it was claimed measures aimed at addressing the problems had been put into place for Australia, former engine chief Andy Cowell admitted they were far from overcome.

“To be honest, Covid came at just the right time,” he told Motorsport.com. “We still had some serious problems with our engine before the start of the first race.”

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Chief designer John Owen also admitted the engine situation was causing alarm within Brackley and Brixworth.

“Our High Performance Powertrains department [HPP] had just discovered a persistent problem and was still searching for a solution," he explained.

“They literally needed one more day, but that time was no longer there prior to [leaving for] Australia.

“The racing season didn’t start in Australia. Soon after, our motor department managed to solve the biggest problems, but it could have been pretty painful if it had just become the first race. We had quite a bit of luck.

“We then brought a new specification of the engine to the Austrian GP, with mainly some reliability upgrades.”

Towards the end of the year some reliability issues again began to creep in, with Sergio Perez suffering failures in Bahrain and Abu Dhabi.

As a result, Mercedes turned down their engines for the final race which perhaps contributed to Max Verstappen claiming a dominant win for Red Bull.