BARCELONA, Spain (AP) With retired champion Nico Rosberg watching from the pits on Wednesday, Valtteri Bottas set the fastest time since layout changes were made at the Circuit Barcelona-Catalunya a decade ago.
The display in preseason testing made another statement about Mercedes' potential in Formula One this season, although Ferrari again remained close.
Bottas, who replaced Rosberg after his surprise departure last year, had a time of 1 minute, 19.705 seconds in the morning session on Day 3 of testing, nearly two tenths faster than the Ferrari of Sebastian Vettel in the afternoon. Red Bull's Daniel Ricciardo was third with his morning lap, nearly one-and-a-half seconds slower than Bottas.
''Another good day in the car,'' Bottas said on Twitter. ''Enjoyed it!''
After the track changes in 2007, when a chicane was added, the fastest lap in Barcelona had been set by Mark Webber's Red Bull in 2010, with a time of 1:19.995 in qualifying. Bottas' time was considered unofficial because it came in testing.
Bottas' fast lap came on the supersoft tires, while Vettel and Ricciardo had their fast times on the slower softs.
Ferrari also showed reliability, as Vettel completed the day's highest number of laps, at 139.
''In terms of laps I think it was decent,'' Vettel said. ''The car doesn't have any major issues in terms of reliability, which is the most important right now. In terms of performance it's impossible to tell, but by the looks of it, we still need to find decent chunks, so a lot of work ahead of us.''
New tire and aerodynamic rules introduced in 2017 to bring more excitement to the series gave cars more grip and downforce, making them significantly faster than in previous years.
But Mercedes is expected to continue to dominate despite the changes. The team had another trouble-free day on Wednesday, with Hamilton driving 95 laps in the afternoon. He focused on race simulation, finishing with the seventh-best time.
Rosberg, who retired in December, five days after clinching the title with Mercedes, was at the track and spent time in the paddock talking to several drivers and teams.
''It was a nice experience for me,'' Rosberg said, adding that he felt no regret about retiring.
Red Bull lost some time in the afternoon session because of an exhaust issue, preventing Ricciardo from driving many laps.
McLaren's Fernando Alonso had a problem-free session after a series of issues on the first two days, although he was reportedly running on lower engine power. He finished with the 10th-fastest time among the 13 drivers who ran on Wednesday.
There was a red flag in the morning session when Jolyon Palmer had a problem with his Renault, and the afternoon run had to be interrupted twice, after Carlos Sainz went off the track with his Toro Rosso and when 18-year-old rookie Lance Stroll lost control of his Williams in his third mistake so far in preseason testing.
The teams return to the track on Thursday for the last time this week. Another four-day session will take place from March 7-10.
The season-opening race is in Australia on March 26.