George Russell thinks Red Bull is now quicker than Mercedes was in 2014, after winning with a convincing margin in the last two Formula 1 races.
At the beginning of the turbo-hybrid era, Mercedes were regularly outclassing the field, with six Mercedes-powered cars finishing in the top 10 at the season opener in Australia.
Red Bull finished over 30 seconds ahead of the competition in Bahrain and continued the large gap in Saudi Arabia, when Sergio Perez was 20 seconds ahead of Fernando Alonso at the chequered flag.
Russell believes work needs to be done by all teams to close the "serious" gap they have created.
"First you've got to give credit to what Red Bull have done, the gap they have to rest in the field I think is bigger than we've seen probably since Mercedes in 2014," he told Sky Sports.
"It's a serious, serious gap and everybody needs to keep working harder to understand how to close that gap."
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Reason for optimism
After realising that they will need to change car concept following a poor start in Bahrain, Mercedes appear to be in disarray as they play catch up to rivals.
Russell has reason for optimism, believing the team has the ability to regain their performance with fundamental changes.
"But we know we didn't make the right decision over the winter and I think we can regain some of that performance quicker than you would do ordinarily," said the Briton.
"So everything's not all lost. We're still going to be fighting as hard as we can, we want to win races this year, we want to be in the championship.
"We will equally want to be realistic, focus on ourselves and just get the fundamentals right for the long term."
Join RacingNews365.com journalists Michael Butterworth and Dieter Rencken, with new host Balve Baines, as they discuss the key talking points from the Saudi Arabian Grand Prix.