Vettel's spark plug puts spotlight back on Renault

Hours after Red Bull diagnosed an exhaust problem as the cause of Sebastian Vettel's Bahrain power loss, the team issued a media statement.

The 22-year-old race leader, having started from pole, fell behind the eventual podium sitters and finished the season opener just fourth.

Red Bull said late on Sunday that "further investigations have proven that the loss of power was actually due to a spark plug failure and not the exhaust".

The statement reminded observers about Red Bull's persistent reliability problems with its Renault engines last year, and ultimately futile efforts over the winter to switch to Mercedes.

"Failed world championship beginning: did Red Bull stumble with Renault?" read a headline in the Swiss newspaper Blick.

And McLaren's Lewis Hamilton is quoted as saying by The Sun: "If Vettel had a reliable engine, he's got so much downforce he could run away with it.

"But if he has problems it won't be a runaway year for anyone," he told the British newspaper.

Dr Helmut Marko, Red Bull's motor sport adviser, said Sunday proved the talent of Vettel and the pace of Adrian Newey's RB6 design.

"What was shown by Vettel in Bahrain after the big horsepower loss was his incredible speed in the corners," he said.

According to Spain's Diario AS, however, Vettel ran out of fuel after crossing the chequered flag on Sunday.

But Ferrari's Fernando Alonso is celebrating cautiously after winning on debut with the famous Italian team.

"Red Bull are still a bit ahead of us," he is quoted as saying by Blick from his home in Lugano.