This week, Italian media suggested Ricciardo had signed a "pre-agreement" deal with Ferrari giving both parties exclusive negotiating rights until June 30, but he was quick to quash those rumours ahead of this weekend's Azerbaijan Grand Prix. The Australian says he would "love to obviously be challenged against the best and Lewis is obviously up there". That would likely mean a switch to either Mercedes or Ferrari.
When asked by Autosport if the curiosity to see what life was like at another team would get the better of him, Ricciardo said: "I don't know. I don't want to say that it's just Lewis I'm looking for, but that would be a good challenge".
Ricciardo, who said he hasn't spoken with Ferrari or Mercedes yet, said he won't accept a faster vehicle if it means playing second fiddle to an established star. "I would expect that environment everywhere".
He is expected to lead another strong Red Bull challenge this weekend on the Baku street circuit in Sunday's edition of the Azerbaijan contest which a year ago delivered a momentous race punctuated by crashes and Safety Car interventions.
The Australian wants to keep his options open for as long as possible as he waits to see which vehicle will give him the best title-winning opportunity, but Red Bull say they need to know his plans sooner rather than later. "I would always show love, nonetheless".More news: Private funeral service for Barbara Bush on Saturday
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If Ricciardo goes to Mercedes, that would nearly certainly mean a departure for Valtteri Bottas, who won three races in his debut season with Mercedes previous year.
The Australian's strong start to the campaign has thrust the Chinese GP victor into the centre of the 2019 F1 driver market situation, with rivals Ferrari and Mercedes having seats available as things stand.
"He is a driver who could be very suitable for a winning team like Ferrari because he is going to "stimulate" Sebastian Vettel, the one that today is definitely the first Maranello driver".
As one of the most sought-after drivers in F1, Ricciardo is in no rush.