Barcelona: Nico Rosberg was fastest in practice for the Spanish Grand Prix on Friday, continuing his dominance in Formula One this season.
Rosberg, who has won the first four races, led Ferrari driver Kimi Raikkonen and Mercedes teammate Lewis Hamilton in the afternoon session.
Rosberg's time of 1 minute, 23.922 was three hundreds of a second faster than Sebastian Vettel's leading time in the morning. Vettel was about a second off the pace in the afternoon, finishing behind Hamilton, who is using new parts to his power unit to try to avoid the mechanical failures that have plagued him this season.
Vettel and Raikkonen were about half a second faster than the Mercedes drivers in the first session, although the times came on softer tire compounds that were not used by their rivals at the time. Raikkonen had to abort a fast lap in the afternoon after the team detected a fuel system problem in his car. Both Ferraris have dealt with mechanical failures this season.
Rosberg, who won from pole position in Spain last year, will be trying to win his eighth straight race, going back to last season. Ferrari hasn't started from the pole in Barcelona since 2008, when Raikkonen was at the front.
Times on Saturday were significantly faster than Rosberg's pole position a year ago.
Rosberg arrived in Spain with a 43-point lead over Hamilton in the drivers' standings. Raikkonen is third and Vettel, who retired in two of the four races, is fifth.
Max Verstappen, who replaced Daniil Kvyat at Red Bull, was sixth-fastest in the morning and eighth-quickest in the afternoon, both times behind teammate Daniel Ricciardo. Kvyat was 12th-fastest in the morning in his return to Toro Rosso, Red Bull's feeder team, and only 15th-quickest in the afternoon, well behind teammate Carlos Sainz.
McLaren driver Fernando Alonso had a promising start to his home race, finishing the second session in seventh place, while teammate Jenson Button was 12th after struggling with handling issues in the morning and enduring a mechanical failure in the afternoon.
Haas driver Romain Grosjean was 13th fastest but said his car a "disaster" and "undriveable." Teammate Esteban Gutierrez was second-to-last in the afternoon.
British driver Jolyon Palmer, who was replaced by test driver Esteban Ocon in the morning session, had a rear tire blow on the front stretch less than 30 minutes into the second session, prompting a red flag.
Spain is where most teams bring new updates to their cars, especially in aerodynamics. Mercedes and Ferrari were able to stay well ahead of the pace at the Circuit de Barcelona-Catalunya, which is where preseason testing took place over eight days in February and March.
