Some paddock figures are toying with the idea that Sebastian Vettel might soon call time on his F1 career.
A number of people have sensed a change with the four-time world champion, who moved to Ferrari last season after spending much of his career as a Red Bull-backed driver.
"Some things we have seen before with him, but it has been a bit more uncharacteristic than in previous years," said Vettel's 2014 team mate, Daniel Ricciardo.
Vettel's former boss Christian Horner has also sensed Vettel's change.
"It is not an attribute he had when he drove for us," he said. "Obviously his frustration he is vocalising, and everybody can hear that."
Neither Vettel or Ferrari are willing to discuss the terms of their new contract. Vettel's deal with the Italian team expires at the end of next year, and former driver-turned commentator Martin Brundle thinks it could be a sign that the German could be heading out of Formula One.
"I'm beginning to think Sebastian Vettel won't be in Formula One for the long haul," he said. "He came so young, he broke so many records. I just watch him at work and he's lost his mojo."
And an unnamed figure told the Times newspaper this week: "Seb could just walk away.
"He has won four titles and he has nothing to prove. He is a private man with a family. He doesn't crave the spotlight and he may think he has had enough.
"It would be a shame, but he could do it."
Bahrain International Circuit - Winter testing
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