MONTMELO, Spain (AP) Red Bull driver Daniel Ricciardo narrowly clocked the fastest time while also putting in the most laps during Formula One preseason testing Friday.
The Australian put Red Bull at the top of the day's timesheet for the first time this preseason by steering his way to a benchmark lap of 1 minute, 24.574 seconds after an early fog broke over the Barcelona-Catalunya Circuit. He also completed a session-high 143 laps.
''I know it's just testing but it is encouraging seeing us on top or at least in that front group,'' said Ricciardo. ''Obviously you have no idea what everyone is doing, but it is encouraging.''
Kimi Raikkonen was 0.01 seconds behind after another promising day from Ferrari, while Williams' Felipe Massa, Sergio Perez of Force India and Mercedes pair Lewis Hamilton and Nico Rosberg were all within one second of Ricciardo.
All but Rosberg bettered Pastor Maldonado's leading lap time from Thursday.
Hamilton was back at the wheel for Mercedes after he withdrew early Thursday because of a fever. The champion took over for Rosberg after lunch with the German having a ''back issue.''
''My back has been a bit of an issue but I know what it was,'' said Rosberg. ''My position in the car was not quite right but I've been lucky with it really and it should be fine for a full day on Sunday.''
Hamilton said that Mercedes had yet to focus on speed.
''The first test was just about completing loads of laps and today was the same, so I've not really started dialing the car into how I'd like to perfect it,'' he said. ''Quick laps are for Saturday in qualifying. But it feels good, similar to last year but better.''
Raikkonen still holds the fastest time through this preseason from the opening tests in Jerez.
Overall, Ferrari continues to show signs it is back and ready to challenge Mercedes after a disappointing 2014. Sebastian Vettel topped testing on two days in Jerez, while Raikkonen has finished in the top two spots through his four days of driving.
McLaren could be thankful its new Honda-powered car held up with Fernando Alonso behind the wheel for 59 laps, the team's highest total for a preseason session. A faulty seal had cut short Jenson Button's shift on Thursday after 21 laps. Honda had then said the car needed a new component that won't arrive until Saturday to ensure its reliability.
Jolyon Palmer, the GP2 champion, debuted as Lotus' reserve driver, completing 77 laps and recording the eighth fastest time- right behind Alonso- of the 10 drivers.
The day's only mishap occurred when Toro Rosso newcomer Carlos Sainz Jr. went off course and into the gravel at turn nine. Sainz, who was the slowest behind Sauber's Marcus Ericsson in ninth, later said it was his own driving mistake that took him off the track.
Testing continues through Sunday. Teams then take a pause before returning to the track for a final four days of testing next weekend. The season begins at the Australia GP on March 15.