Mercedes ended the final day of 2013 preseason Formula 1 testing on top thanks to Nico Rosberg.
The German recorded a 1m20.130s at Barcelona on soft tyres after trading fastest laps with Ferrari's Fernando Alonso for much of the morning session.
Most teams concentrated on higher fuel runs or the harder tires in the afternoon, so there were few improvements after the break. That meant the top duo's advantage remained at around one second, with Jenson Button's McLaren third from the Sauber of Nico Hulkenberg.
Force India's Paul di Resta finished the morning in fifth, but was knocked down a place by one of the few improvers of the afternoon.
Kimi Raikkonen's Lotus spent most of the morning in the pits thanks to a gearbox problem. A couple of soft-tire runs toward the end of the afternoon nevertheless lifted him to fifth.
The only other changes to the times in the afternoon came from drivers who had not been part of the morning session. Valtteri Bottas took over from Pastor Maldonado at Williams and was just over 0.1s slower than the 2012 Spanish Grand Prix winner as the FW35 took seventh and ninth.
At Marussia, Max Chilton took over from Jules Bianchi. A late improvement meant he recorded 1m24.103s, but that was almost a second slower than his new team-mate's best from the morning.
Red Bull again proved difficult to read. A mix of unmarked tires and harder rubber meant Sebastian Vettel never went for a headline time and thus ended up eighth.
Pos Driver Team Time Gap Laps
1. Nico Rosberg Mercedes 1m20.130s 131
2. Fernando Alonso Ferrari 1m20.494s + 0.364s 120
3. Jenson Button McLaren 1m21.444s + 1.314s 122
4. Nico Hulkenberg Sauber 1m21.541s + 1.411s 118
5. Kimi Raikkonen Lotus 1m21.658s + 1.528s 50
6. Paul di Resta Force India 1m21.664s + 1.534s 112
7. Pastor Maldonado Williams 1m22.415s + 2.285s 42
8. Sebastian Vettel Red Bull 1m22.514s + 2.384s 100
9. Valtteri Bottas Williams 1m22.524s + 2.394s 31
10. Charles Pic Caterham 1m23.115s + 2.985s 116
11. Jules Bianchi Marussia 1m23.167s + 3.037s 62
12. Daniel Ricciardo Toro Rosso 1m23.628s + 3.498s 91
13. Max Chilton Marussia 1m24.103s + 3.973s 49
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