Sep.20 (GMM/ As Mercedes’ long and dominant form mysteriously disappeared under the Singapore floodlights, it did not take long for the speculation to begin.

Everyone at Marina Bay and beyond could not believe that, just two weeks after the utter domination of Monza, the silver cars are suddenly much slower than Ferrari and Red Bull.

“When I saw Sebastian (Vettel’s) time I thought ‘What the hell?'” admitted Nico Rosberg after qualifying. “We did not see this coming.”

The German admitted that, in the past couple of years of Mercedes’ utter domination of the ‘power unit’ era, the Singapore situation is unprecedented.

“We had a dominant car and now we are one and a half seconds behind. Unbelievable,” said Rosberg.

“I just looked at Vettel’s onboard lap, and it’s like he’s in a different category.”

Lewis Hamilton, whose shot at equalling hero Ayrton Senna’s victory tally on Sunday now appears unlikely, called for Mercedes to look urgently into the matter.

“I don’t know really what we’ve got wrong,” said the championship leader.

The early paddock theory is that, having dominated at Monza but only narrowly avoiding disqualification over the tyre pressure saga, Mercedes is now struggling for pace as Pirelli strictly enforces the new guidelines.

“These tyres for some reason aren’t working on our car,” Hamilton said in Singapore. “I’m challenging my team to find out what it is, whether it’s tyre pressures or temperatures or blankets or ride heights, I’m asking.”

Team boss Toto Wolff, however, scoffed at rumours Mercedes was only dominating before because it was regularly skating beneath Pirelli’s tyre pressure guidelines.

“It’s no conspiracy. It’s paranoia,” he insisted. “We didn’t do anything dodgy. It was cleared by the FIA. The Pirelli limits were no contributing factor to our performance,” Wolff added.

He acknowledged, however, that Mercedes now has crucial work to do to understand the true cause.

“It is not just for the race here, which will be very difficult anyway even though we will give everything, but it is very important that we do not make the same mistakes that we made here in the next weekends,” the Austrian said.