Mercedes team principal Toto Wolff has declared "the fight is on" between his team and Red Bull after Max Verstappen secured pole position for the Bahrain Grand Prix.
The German manufacturer's worst fears from pre-season testing at the same venue were realised in qualifying as the Dutchman romped to the top spot by almost four-tenths of a second over Lewis Hamilton.
Despite the gulf between the two performances, Wolff was non-committal as to whether there had been a role reversal between the two teams over the winter.
"Every deficit is difficult to take and is it a reverse [of last year]? We don't know," said the Austrian.
"It is the first race of the season, Red Bull has a quicker car in qualifying in Bahrain than us. I am proud of how we have recovered from the test that was sub-optimal. The fight is on."
Red Bull's engine supplier Honda brought forward the introduction of a new power unit to the start of this year following its decision to pull out of the sport at the end of the campaign.
Wolff praised the Japanese manufacturer's work, saying it had done a "great job" and adding: "It has delivered a power unit that is extremely competitive.
"Look at where AlphaTauri is. We just have to take it as sportsmen. This is as it looks, we just have to say they have done a really good job, full stop. There is just no other solution than to recover."
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