MONTMELO, SPAIN - MAY 09: Sebastian Vettel of Germany and Infiniti Red Bull Racing helps to push his car off the track after breaking down during practice ahead of the Spanish F1 Grand Prix at Circuit de Catalunya on May 9, 2014 in Montmelo, Spain. (Photo by Clive Mason/Getty Images)

Barcelona, Spain - Red Bull's decision to change Sebastian Vettel's car for the Spanish Grand Prix backfired on Friday when an electrical problem sidelined the four-times Formula One world champion for most of practice.

With race favourite Lewis Hamilton fastest in the morning session for dominant Mercedes, Vettel was forced to park at the side of the circuit early on, after completing just four laps.

Circuit de Catalunya marshals handed him a fire extinguisher as he inspected the car before hitching a ride back to the paddock on a scooter.

And before the afternoon session started his team announced: “Due to an electrical problem that has damaged the wiring loom of Car No. 1, Sebastian will not be able to take part in FP2 (second practice),” .

“The Team will use the time to fix it to be ready for FP3 (the final session before qualifying) tomorrow.”

Vettel, winner of the final nine races of 2013 and four championships in a row, has had a difficult start to the new V6 turbo era with Red Bull's engine partner Renault playing catch-up with Mercedes.

The last time Vettel was in action at a Spanish circuit, testing at Jerez in January, he spent most of his time in the garage watching mechanics work on the car.

Hamilton, winner of the past three races and closing in on championship-leading team-mate Nico Rosberg, went from strength to strength with a fastest lap of 1m27.023, set six minutes from the end.

That was 0.868 quicker than Jenson Button, who was best of the rest for McLaren, and the impressive margin on a sunny morning further underlined the Briton's status as the man to watch.