(AFP) - Ferrari's Sebastian Vettel outgunned reigning world champion Lewis Hamilton to the fastest time as the 2016 Formula One season got underway with the the first test in Barcelona on Monday.
The Italian giants are expected to pose an even stronger challenge to Hamilton's Mercedes this season after Vettel showed signs of a Ferrari revival by winning three races last season.
The four-time world champion was nearly half a second faster than Hamilton in a time of 1min 24.939sec.
However, after dominating the sport for the past two seasons, Mercedes' reliability sent another warning shot to the rest of the paddock as Hamilton ran the most mileage with 66 laps before lunch.
Williams were again the best of the rest as Valtteri Bottas was third fastest.
Mclaren-Honda made a significant improvement on their disastrous performances in testing last season which set up a hugely disappoining return season to the sport for the Japanese manufacturer.
Jenson Button managed 35 laps, but the MP4-31 was still well down on pace nearly three seconds behind Vettel in sixth fastest.
Haas, the first American-owned team in Formula One for 30 years, took their first tentative steps as Romain Grosjean logged 13 laps, but his session was ended prematurely by a broken front wing that temporarily stopped running.
Manor Racing were the only team to struggle mightily as new German recruit Pascal Wehrlein managed just seven laps and was over six seconds adrift of the field.