Nico Hulkenberg set the fastest time on the opening day of the second test in Bahrain as Red Bull hit more trouble.

On a productive day for Force India during which he completed 78 laps, Hulkenberg set a time of 1:36.880 on the soft compound tyre to head the field by a just shy of a second. Fernando Alonso was second for Ferrari - 0.999s off Hulkenberg - ahead of Lewis Hamilton who saw his running come to an end with over two hours still to run.

Hamilton's problem was not specified by Mercedes but came after he had already completed 74 laps and been quickest. Kevin Magnussen ended the day fourth fastest, just under 0.4s slower than Hamilton, but had the second-highest lap total with 81; one shy of Adrian Sutil in the Sauber.

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It was another tough day for Red Bull, as trouble fitting new parts to the RB10 prevented the team from running at all in the morning. Vettel did get out on track in the afternoon but had only managed 14 laps when he caused a red flag with less than 90 minutes to go after spinning off and didn't emerge again.

Vettel was far from the only driver to hit trouble though. Alonso caused the first red flag of the day after leaving the pits with smoke emitting from the rear of his Ferrari, while Sutil had a spin at Turn 1 that brought another stoppage after three hours of running.

The Lotus E22 made its public debut on Wednesday morning but after quickly completing seven laps the car didn't return to the track, with the team admitting it was closely following Renault's advice following recent power unit issues. However, Caterham managed 68 laps with Robin Frijns at the wheel to give Renault its most productive day of pre-season so far.

As well as Red Bull, Toro Rosso's problems continued with Daniil Kvyat being confined to the garage even longer than Vettel and managing just five laps before he stopped with an electrical problem. After an impressive Jerez test, Williams also had trouble as a fuel system issue restricted Felipe Massa to just five laps, while Jules Bianchi had the lowest total of the day with three laps for Marussia.

An unconfirmed delay at the start of the day meant running to underway half an hour later than planned and ran until 17:30 local time, with the final laps taking place as darkness fell.

Day one times available HERE.