Daniel Ricciardo could be headed to Mercedes for 2019.
It is believed one of the reasons Red Bull was so keen to extend Max Verstappen’s deal through 2020 is that Ricciardo is - in Helmut Marko’s words - "on the market" for a new team after his current contract expires late next year.
Ricciardo, 28, is not denying it, although he does play down speculation a move to F1’s other top team Ferrari may be likely.
"I’m always asked about Ferrari," he said, "but I have the impression that the interest comes through the fans or the media rather than from Ferrari itself."
Rumours Ricciardo is on the move have ramped up ever since Red Bull boss Christian Horner said he is prepared to "build the team" around Verstappen, 20.
Ricciardo said in Austin: "If I was to negotiate with another team, one of the first issues would be insisting on identical conditions.
"If someone said ’We’ll sign you but you’d have to support your teammate’, I wouldn’t sign."
Horner, however, has warned Ricciardo that if he does go to Mercedes or Ferrari, he would in effect be the ’number 2’ behind Lewis Hamilton or Sebastian Vettel respectively.
But Ricciardo said he is not afraid of Hamilton.
"Obviously I’ve had the chance with Seb," he said, "and I’ve had it with Max.
"While Lewis is in his prime I would like to challenge and see."
Mercedes is keeping Valtteri Bottas on board for 2018, but boss Toto Wolff is keeping his options open for 2019.
Hamilton is happier since Nico Rosberg retired, but Wolff admits that a "nuclear" teammate relationship can often push a team forwards.
"If your drivers get along, you do not have to deal with their skirmishes all the time," he told TZ newspaper.
"The question is what happens next. Do we want to keep this team dynamic? Or is the nuclear variant better for us?"
When asked specifically about Ricciardo, Wolff answered in Austin: "We have just extended with Valtteri and we haven’t thought beyond 2018."