Day 4 - Jerez Report: Massa demonstrates Williams pace

The fourth and final day of testing at Jerez got underway this morning with a wet and overcast track, leaving the teams to have a second chance at testing the wet Pirelli tyres.

It was all change once again regarding the drivers line-up with Kamui Kobayashi getting his first run in the Caterham, likewise for Force India reserve Daniel Juncadella. Jules Bianchi also took over from Max Chilton at Marussia as well as Kvyat for Toro Rosso.

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Mercedes' Nico Rosberg was first out for an installation lap, followed by Adrian Sutil's repaired Sauber and Daniil Kvyat's STR9. Red Bull's Daniel Ricciardo also completed his first timed-laps later in the morning after a troubled debut yesterday.

McLaren, Mercedes and Ferrari had a highly successful day, completing over 100 laps each and showing some very respectable pace. Although, the German Mercedes outfit had two drivers on track as opposed to one each from their British and Italian counterparts.

Despite a promising start, Red Bull's gremlins continued today. After completing only 7 laps the team reportedly suffered another mechanical issue and decided to pack up in a bid to try and get their problems sorted for the next test in Bahrain.

The Red Flag appeared to be the FIA's favourite flag of the day once more, making an appearance three times, the first being courtesy of Sutil once again spinning in his Sauber. Magnussen also thought spinning seemed like a good idea, with the Dane dropping the MP4-29 in the middle of Turn 12.

His car was quickly recovered and Kevin was able to make it out for the final hour of the test. However, eight minutes before the session ended, he went off again in Turn 10, this time colliding with the barriers. Daniil Kvyat's Toro Rosso also ground to a halt at Turn 10 moments after the incident.

It was the Williams of Felipe Massa who claimed top honours today showing the FW39's true pace. The Brazilian was almost a second quicker than Alonso's F14 T and more than +1.2 seconds ahead of Juncadella's Force India, who showed some very impressive speed and potential for the VM07.

F1Today.net will have a round-up of the weeks' events that is scheduled to be posted tomorrow morning, featuring an in-depth analysis of each teams' week as well as statistics regarding the new V6 Turbocharged power units.