Sebastian Vettel described his car problems on Friday as a “small failure with big consequences” after missing most of the day because his Red Bull suffered electrical problems.

He had to watch as young teammate Daniel Ricciardo finished best of the rest behind the all-conquering Mercedes team.

The defending four-time world champion only did four laps in opening practice at the Spanish Grand Prix and missed the afternoon session entirely as Lewis Hamilton and Nico Rosberg topped the times with ease.

Ricciardo wound up nine-tenths of a second off Hamilton’s pace and said he felt “frustrated” by the gap.

“We are making progress, but unfortunately Mercedes don’t seem to be slowing down either, so they are a little bit far away,” Ricciardo told reporters.

“A little bit frustrated. Surprised, I don’t know, as they have been so strong already. I hoped we would probably close the gap a bit more. Today, it was too far. We are trying to pull them back, but we seem to be in a solid third place today.”

Vettel played down the significance of his problem, saying that the complicated internals of the car made it seem like a bigger issue than it was.

“It is a small failure with big consequences,” he said. “We decided to change the whole (electrical wiring) loom and unfortunately that is a pretty big change.

“It was rubbing a bit which caused damage and caused the short, and made the car stop. There are sensors everywhere so it takes a while to strip the car and take everything apart.”

He added that he expects Red Bull to make up for the lost track time.

“I hope we can recover, otherwise it would be sad news,” he said. “I’m confident we should be fine.”