World champion Sebastian Vettel has laughed off pit-lane rumours about the superior pace of his Red Bull car as his main rival, Fernando Alonso, also dismissed whispers that the German is benefiting from illegal driver aids.
Traction control systems are now banned but Vettel's pace in Singapore last month was so astonishing, with his car pulling out a 30-second lead in the space of 15 laps, that speculation was still buzzing ahead of this Sunday's Korean Grand Prix.
Mercedes' Lewis Hamilton said that the last time he had a car that could perform like Vettel's was when traction control systems were legal, although he did not accuse Red Bull of anything underhand.
Former team owner Giancarlo Minardi fuelled the speculation last week, when he suggested Vettel's car in Singapore had sounded different to all the others, including his team-mate Mark Webber's. "That sound was similar to the sound made by the engine when the traction control system got into action in the past seasons," Minardi added.
Ferrari's Alonso, Vettel's closest title rival but 60 points adrift, said the Red Bull engine had sounded different all season but was maybe highlighted in Singapore because of the nature of the street circuit.
"If you go to the winter tests in Barcelona, in the corners the Red Bull had a different sound," he said. "So they are using something different compared to the other teams but it's something that is completely okay.
"They pass all the checks every race so it's up to us to do better."
Vettel, who could wrap up his fourth successive title this month, simply smiled when asked whether he would be as dominant in Korea as in Singapore. "Well, since traction control will not matter so much, we may struggle a little bit more," he told reporters with tongue firmly in cheek.
Asked in a later question about Red Bull's 2014 car, the 26-year-old returned to the theme. "There's elements of this year's car going in to next year's... things like traction control will obviously be..." he grinned. "We are pretty proud of the system we have because other people will never figure out how we've done it."
Something was clearly bothering Hamilton, who presented the demeanour of a man with the weight of the world on his shoulders. But it was his comments on Vettel that only heightened the ongoing speculation about the Red Bull car.
"I think that Singapore was the true form of the Red Bull," Hamilton conceded. "After a restart behind a safety car everyone is going flat out. But he [Vettel] was flat on the throttle at least 20 metres earlier than anyone else. That's a huge advantage.
"The last time I could nail a car's throttle like that was with McLaren in 2007 or 2008, when we had traction control."