Fernando Alonso set the pace on the opening day of Formula One testing at Valencia as Renault continued the development of their R28.

The 2005 and 2006 world champion completed 39 laps of the Spanish circuit on a day that saw his running curtailed until midday as a layer of thick fog coated the track throughout the morning.

But the 26-year-old Spaniard did still manage to set the pace in 1:13.027 as he focused on the checking of electrical systems on his car.

"When you have your first day with a new car, you always have to take your time to check that all the systems are functioning correctly, and that is what we did today," said Alonso.

"We were able to lengthen our runs little by little and ended the day with a 14-lap stint. Everything went well, but it is still too early to try and compare our performance with that of other teams, and that was not the objective today.

"The good news is that we encountered few problems, and we will be able to continue our work tomorrow."

Alonso's pace was 1.4 seconds quicker than that set by Williams test driver Nico Hulkenberg.

The German was giving his team's new FW30 its maiden run after it was officially launched early in the morning.

He blotted his copybook with a trip into the gravel at turn one, which broke the car's floor and forced him into the garage for an hour.

Hulkenburg managed 20 laps during the day.

Testing continues for another three days, with seven more teams racking up at Valencia - including McLaren, who will have the newly re-signed Lewis Hamilton at the wheel of their MP4-23.

Jamie O'Leary / Eurosport