Sebastian Vettel must beat friend and new Ferrari teammate Kimi Raikkonen in 2015.
That is the claim of former F1 driver David Coulthard, who fears the quadruple world champion cannot afford to lose another internal battle this year.
Now, he is paired at the fabled Maranello team with his friend and Finn Raikkonen, who also notably struggled in 2014.
Coulthard told Germany's Sport Bild that Vettel cannot afford to be beaten again.
"He needs to be faster," the Scot said.
"If he's not, frankly: it's his career (in jeopardy)," said Coulthard.
In total contrast, Australian Ricciardo's career is cresting a wave at present, as he rides the perception that he is better than Vettel at adapting to a car.
"So far," he confirmed to Brazil's Totalrace, "I have managed to adapt to any car that I have driven. Maybe because I like new challenges.
"I don't know what the limit is," Ricciardo added. "I don't know if it would work with a rally car, but at least in single seaters, I've managed to adapt."
Ricciardo demonstrated his apparent adaptability in style last week, when he smashed Lewis Hamilton's track record in the Suzuki Liana during an appearance on the popular British motoring show Top Gear.
"Absolutely staggering," the BBC programme's host Jeremy Clarkson told the F1 star. "How did you do that?"