Montmelo, Spain: Reserve Alfa Romeo driver Robert Kubica was fastest as Formula One preseason testing resumed Wednesday at the Barcelona-Catalunya Circuit.
Kubica had a time of 1 minute, 16.942 seconds, becoming the first driver other than Mercedes teammates Lewis Hamilton and Valtteri Bottas to go faster than 1:17.000 this year.
Alfa Romeo driver Kimi Raikkonen had led one of the tests sessions last week.
Mercedes continued to show good reliability, with Hamilton's 88 laps being the most among all 10 drivers who went to the track in the morning. The defending champion was fourth-fastest.
Pierre Gasly of AlphaTauri was second, nearly six tenths of a second slower than Kubica, with Red Bull driver Alexander Albon finishing third.
Ferrari driver Sebastian Vettel was sixth, but he ran 84 laps in the morning. He caused the first red flag of the day, though, after running wide and losing the rear of his car.
Kubica also spun out early in the morning session.
Mercedes was dominant in the first week, setting the fastest times and running the most laps " 494. Bottas led the time charts with a lap of 1:15.732 seconds.
Mercedes also attracted attention last week by introducing a novel steering system in which drivers pull the steering wheel back and forth to adjust the angle of the front wheels on straights.
Some teams on Wednesday tested the prototype Pirelli tire which was being developed specifically for the banked corners that drivers will encounter at the Zandvoort track that will host the return of the Dutch Grand Prix in May.
The season begins with the Australian GP in Melbourne on 15 March. It is the last before new regulations are put into place in 2021 to try to provide a more level playing field.
Preseason testing has been reduced from eight to six days to help compensate for the record 22 races on the calendar, including a new Vietnam GP and the Dutch GP. Midseason testing also has been eliminated.
The Barcelona-Catalunya track will host the Spanish GP on 10 May.