Italy - Ferrari has set off 'alarm bells' at triple back-to-back world champions Mercedes after victory in Bahrain.
That is the admission of Niki Lauda, the Formula 1 legend and Mercedes team chairman and co-owner.
Sebastian Vettel and Lewis Hamilton traded victories in Melbourne and China, but it was Vettel's win last weekend in Bahrain that has Mercedes worried, Lauda admits.
Lauda told Osterreich newspaper: "The alarm bells are ringing with us.
"Those who win in Bahrain have a certain buffer for the next three races."
Indeed, both Hamilton and his Mercedes teammate Valtteri Bottas admitted in Bahrain that the main problem with the 2017 car is the new Pirelli tyres, particularly in hotter weather.
But others think Ferrari has simply given quadruple world champion Vettel a tantalising sniff at a fifth title.
Gerhard Berger told Sport Bild: "The Vettel factor can decide the world championship this year."
Goodnight from @BAH_Int_Circuit ????April 19, 2017
The former F1 driver admitted he is surprised with Ferrari's pace so far in 2017.
Berger added: "I would have lost every bet before the season, because I doubted that Ferrari would really beat Mercedes."
Another of Vettel's former chiefs, Dr Helmut Marko, agrees: "Sebastian is at one with his car.
"He is constantly on the limit, not making the smallest mistake and always knowing what to do. This is pure driving pleasure for him.
"Like this, Vettel is very hard to beat - especially when Mercedes is making mistakes."
Finally, an unnamed current F1 driver also tipped Vettel to emerge with spoils at the end of a long head-to-head with Mercedes' Hamilton in 2017.
The driver added: "Hamilton lacks the bite. You can only rely on talent alone when you have a car that is a second faster. Three tenths per lap is not enough to beat a Vettel."