Troubled day for Toro Rosso duo

Liuzzi finished the afternoon session down in 19th place after a hydraulic problem caused his power steering and his throttle to not work properly.

"This morning I was quite happy with the balance of the car, particularly over long runs," said Liuzzi.

"Then in the afternoon, we worked on tyre comparisons and this session did not work out quite as well, because we had a problem with the hydraulic system, which unbalanced the car and the power steering and the throttle were not working properly.

"So from the mid-point of the session our work was not so productive. We will have to work on this tonight as up until this problem, everything had been going well."

Vettel also hit trouble during the day after a sensor broke, costing him some valuable track time in the afternoon. The German finished in 20th.

"This morning we struggled a bit to find the right way to progress with the car, but we were still optimistic about improving in the afternoon," he said.

"Unfortunately, a sensor broke deep inside the gearbox which meant we had to pull the back end off the car and replace the sensor and that cost us some time, but fortunately the red flag period meant I did not lose so much time compared to the others.

"Once back on track, we concentrated on acquiring as much data as possible in the short time remaining. In general, I think there is still room for improvement."