David Coulthard has warned that Daniel Ricciardo's F1 career may be over if he doesn't "rebuild" at Red Bull.
Ricciardo was left without a seat on the grid for 2023 after his multi-year contract at McLaren was brought to an early end, with the team opting to bring in rookie Oscar Piastri in his place.
It was later confirmed in November that the Australian would return to the Red Bull fold as a reserve driver for the year ahead.
During his previous tenure on the outfit's race team, Ricciardo scored seven of his eight Formula 1 victories as well as claiming numerous podiums and points finishes.
He left the squad at the end of 2018 to join Renault, where he raced for two seasons before beginning his difficult spell with McLaren in 2021.
Coulthard believes it is important for Ricciardo to rediscover the mindset he had during his winning days at Red Bull in order to better his chances of a succesful F1 return in the future.
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Coulthard assesses Ricciardo's chances of return
"Daniel, not being where we knew he could be – he just didn't look like Daniel of old so this is about him trying to rebuild," Coulthard told the BBC.
"He has a great legacy with Red Bull and he left to go off and try and make it big elsewhere, that didn't work so he has come back to the family.
"If he can get his mind back to what is was when he was having success, then Daniel has to have an opportunity to come back.
"If this opportunity doesn't manifest itself then that's probably his Grand Prix career wrapped up."
Coulthard is not the only former driver to give their take on Ricciardo's future. Mark Webber has suggested that rejoining Red Bull could be a "great opportunity" for his countryman to find his motivation again.
In his role, Ricciardo will help the team with simulator and testing work as well as taking part in commercial activities.