Mercedes team principal Toto Wolff says his squad has been busy aiming to resolve its power unit reliability niggles ahead of the 2020 Formula 1 opener but can’t be certain it has fixed the issue until the season starts.

Both the works team and Williams saw its pre-season testing programmes stalled by numerous mechanical issues with its power unit which triggered concerns over reliability going into the lengthy 2020 season.

Mercedes got through two power units inside five days of running after Valtteri Bottas suffered an electrical fault in the opening week, before teammate Lewis Hamilton stopped on track with a loss of power on the penultimate day. At Williams, the team sustained four engine-related issues across the full six days of testing with the team holding its hands up for one due to a sensor problem.

The reigning F1 world champions have duly run thorough investigations into the issues following testing and while Wolff remained tight-lipped on the fixes he was pleased to see the faults surface during testing rather than on race weekends when drivers would be at risk of engine penalties.

“We managed to get through most of our programme as planned at the winter tests; however, we faced some reliability issues that we needed to resolve,” Wolff said. “We’re glad that we encountered these issues in testing rather than at a race weekend as we could work on fixing them without any penalties.

“It’s finally time go racing again and we’re looking forward to the new season. The team has worked very hard to build a new car and we’re excited to see what it can do when it’s driven in anger.”

Wolff is also wary of balancing its 2020 efforts alongside its preparations for the F1 rules overhaul arriving in 2021.

Mercedes and Hamilton are targeting their respective seventh F1 world titles this year to maintain its era of dominance in the sport before the rules shake-up.

“The new season will be exciting to watch both on-track and away from it as everything we do this year will have a knock-on effect for our competitiveness in the future,” Wolff said.

“We face the challenge of the biggest technical changes our sport has ever seen combined with a budget cap, so the work that we do this year will determine the start to 2021.

“This makes the 2020 season a massive challenge - a challenge that everyone in Brixworth and Brackley is looking forward to.”

Bottas claimed victory for Mercedes at the Australian Grand Prix 12 months ago, breaking a run of consecutive Ferrari victories at Albert Park, which started a run of eight straight Silver Arrows triumphs at the start of 2019.