Ricciardo took the plunge and left Red Bull after a decade under the team’s guidance, half of which was in the senior squad, and signed with Renault for the 2019 and 2020 seasons, citing the need for a new challenge.
Vettel is now into his fifth season at Ferrari, but his 2019 has come with much frustration as the Scuderia have failed to keep pace with Mercedes, leaving the German facing another year where defeat to Lewis Hamilton looks likely.
It has prompted wild reports that Vettel could even retire from F1 at the end of the year – with Ricciardo mentioned as a potential replacement.
And Ricciardo says he can empathise with any negative thoughts coming to his former team-mate.
“Maybe he’s experiencing something like what I felt a year ago: frustrated and vulnerable,” Ricciardo told Corriere della Sera.
“But he remains a fast driver and can always win a title. The only doubt: does he still know how to keep up top form across a season?”
Ricciardo and Vettel were colleagues at Red Bull in the 2014 campaign, which saw the latter’s run of championship success come to an end as Mercedes’ dominance in the V6 Hybrid era began.
“In some situations he had a loss of motivation, seeing that he could not impose himself,” Ricciardo explained.