On the back of a campaign where Ferrari and Red Bull had been putting it under increasing pressure, Mercedes was in a class of its own around the European Grand Prix venue.

Its advantage was often in excess of one second per lap, something that had not been seen since the German car manufacturer hit the ground running in the first year of the turbo hybrid rules in 2014.

When asked why, on the back of a season when the opposition had been closing in, Mercedes were so far ahead in Baku, Rosberg said: "We don't know unfortunately.

"But it is something we have to try to understand, because it was pretty unbelievable here this weekend how fast our car was."

Mercedes boss Toto Wolff reckoned that his team's advantage at the weekend was exacerbated by it simply having found the right set-up window immediately.

"We put the car in the right place on the track on Friday," he explained. "You can see that in some places you go and straight away you seem to have found a sweet spot.

"This track is a combination of high speed and low speed so for power units there is a dominant role of harvesting and deploying energy, and driveability on the engine side, plus aerodynamic efficiency.

"We are not talking of maximum downforce, it is not needed here. And overall that is what gave us that benefit and it was one of our best tracks since 2014."