Mercedes says reliability must now crown 2014 champion

The German went into the night race with a clear points lead and as the drivers' title favourite with six races to go, but faulty electronics left his steering wheel controls in disarray and he ultimately retired.

Sunday's problem - an electrical connection to the steering wheel - was an unusual one, team boss Toto Wolff admitted.

"A mechanic told me that we have been using the same thing since the Honda days and we've never had any problems with it," he admitted to Germany's Welt newspaper.

Teammate Lewis Hamilton has now taken a 3-point lead with five races to go including the double points finale in Abu Dhabi, but the Briton has also suffered problems in 2014 with the otherwise utterly dominant W05 car.

Mercedes' shocking reliability helps Ricciardo

Before Sunday's race, Red Bull team boss Christian Horner was playing down Daniel Ricciardo's chances of having even a remote shot at beating Rosberg or Hamilton.

But now he admits: "Due to their (Mercedes') shocking reliability, hopefully we can keep ourselves in the championship."

Mercedes' technical boss Paddy Lowe says it is something the Brackley based team must address.

"I've said internally from the beginning of the year, when it was clear we had the dominant car, that my biggest concern is that we will decide the championship on the basis of car breakdowns," he is quoted by the Guardian.

"I'm not going to pretend it's good enough because it isn't. It's one of the weaknesses that we have.

"We're doing a lot of work behind the scenes to turn it around but it's a long-term project."

Reliability will decide who is the champion?

Realistically, Mercedes is almost guaranteed wins in both the drivers' and constructors' championships this year, but the manner of the victory is also important to the German carmaker.

"The trouble at the moment is that Nico has seen his championship lead wiped out in one afternoon," said Lowe.

So if it is ultimately perceived that either Hamilton or Rosberg is the eventual points winner based mainly on reliability, "That is something that would not be satisfying at all," Toto Wolff acknowledged.

"We don't want any spin in there that the championship was decided because one car let down the driver," Mercedes' team boss added.