Lewis Hamilton comfortably topped the morning running during the third day of Formula 1 testing in Bahrain.
The Mercedes driver was well clear of the rest of the field as his team sent him out for short runs that were focused on trying different set-ups.
Hamilton adopted the tactic of slowing for a cool-off lap in between his faster efforts, something that Jenson Button was also doing for McLaren at the same time.
The two silver cars were setting the pace with that strategy, although Button was eventually usurped for second by Esteban Gutierrez's Sauber.
New Lotus signing Pastor Maldonado got his first taste of the team's E22 in public, as the Enstone outfit set to work on recovering the lost ground from a difficult first couple of days with Romain Grosjean.
Maldonado was relatively active on track in the early part of the day, but he then spent a long time in the pits after reaching 18 laps.
The E22 briefly returned to the track shortly before 1pm local time, but it was not out for long before stopping and causing a red flag.
Another team experiencing delays in the morning was Force India. Sergio Perez was the last driver to take to the track as his crew was held back by overnight work taking longer than it expected.
Daniel Ricciardo got a few laps on the board as he took over Red Bull's troublesome RB10 from Sebastian Vettel, but the world champion team continued to run at a cautious pace as it tries to get some mileage on the board.
Aside from Marussia, which caused the only red flag of the morning when Max Chilton came to a smokey halt at Turn 4 early on, the team with the least laps in the morning was Ferrari.
Kimi Raikkonen made a handful of appearances on track early in the day, but by the halfway stage he had only 12 laps to his name and was seven seconds off the pace set by Hamilton.
The Williams of Valtteri Bottas topped the lap count, although the Finn did not post a time as the team focused on pitstop practice for its race crew.
Pos Driver Team Time Gap Laps 1. Lewis Hamilton Mercedes 1m34.263s 25 2. Esteban Gutierrez Sauber-Ferrari 1m37.180s +2.917s 45 3. Jenson Button McLaren-Mercedes 1m37.258s +2.995s 28 4. Pastor Maldonado Lotus-Renault 1m39.642s +5.379s 19 5. Sergio Perez Force India-Mercedes 1m40.339s +6.076s 17 6. Daniel Ricciardo Red Bull-Renault 1m40.781s +6.518s 23 7. Daniil Kvyat Toro Rosso-Renault 1m40.801s +6.538s 27 8. Kimi Raikkonen Ferrari 1m41.336s +7.073s 12 9. Marcus Ericsson Caterham-Renault 1m43.602s +9.339s 33 10. Max Chilton Marussia-Ferrari 1m46.672s +12.409s 4 11. Valtteri Bottas Williams-Mercedes no time 55