Nico Rosberg should be 'looking over his shoulder' as he starts the final year of his Mercedes contract, Damon Hill has warned.
Rosberg's current deal with Formula One's world championship-winning team expires at the end of this season.
The German, 30, joined the Silver Arrows in 2010, and recently said he expects to stay there for "many more years".
But Hill, the 1996 world champion, believes Rosberg, beaten by team-mate Lewis Hamilton in each of their three seasons together at Mercedes, could be replaced by the likes of Pascal Wehrlein or Max Verstappen.
"I would probably be looking over my shoulder if I was Nico," said Hill ahead of Sunday's curtain-raiser at Melbourne's Albert Park on Sunday.
"The problem is, that if you keep things static then they can get stale.
"It is like when Lewis left McLaren, Nico has been at Mercedes for a very long time and has been a loyal servant, but he might be able to command a bit more respect if he went to his own team or a team where he could be more prominent."
Wehrlein is a product of the Mercedes driver academy and was the understudy to Hamilton and Rosberg last year.
But the 21-year-old German will make his full grand prix debut on Sunday after landing a full-time seat with Manor this season.
The British-based team, backmarkers for much of their tenure in Formula One, are expected to move up the grid in 2016 after agreeing a deal to use Mercedes engines.
And asked what Wehrlein would need to do to encourage the Mercedes' hierarchy to team him with Hamilton, Hill added: "He needs to show speed and not to make too many mistakes.
"Mistakes are forgiven if you are quick. Like Max, he is clearly got the confidence, the talent and the ability and if you have got those things the odd blip is going to be forgiven, but without the speed the roof caves in pretty quickly."
Mercedes boss Toto Wolff has revealed that the team will have to reassess their driver line-up should Hamilton and Rosberg's fractious relationship continue to deteriorate.
But speaking at the team's kick-off in Stuttgart last week, Wolff said: "Nico is part of the family and we have not started any discussions elsewhere.
"We owe it to our driver to open up these discussions with him before talking to anyone else and understand where he sees his future. We have kept it as little away from him now so he can concentrate on the championship."
*Sky Sports F1Â® is the only place to watch all 21 races live of the biggest ever season, beginning in Australia 17-20 March