Mark Webber has once again activated the warning signals over Daniel Ricciardo's pending move to Renault in 2019.

The Australian has already pondered if the French manufacturer is a good long-term option for his fellow countryman, who'll leave Red Bull after a total of 10 years as a member of their stable.

And now, after the mental impact of eight retirements this season which included Ricciardo declaring his year "done" after Mexico, Webber wonders if the 29-year-old can take another year of frustration.

"I think it’s quite obvious he can’t wait for the season to be over, which is a little bit of a concern. I don’t want him to fall out of love with the sport," he told Australia's The West.

"I just think that really tests your mettle and he’ll be questioning the sport in his head. There’s not too many people to put an arm around your shoulder. Only the tough survive and he knows that.

"He’s got to buckle up and keep going if he wants to bounce back with Renault next year."

Also Read:

• Ricciardo confirms participation in final two races after Mexico outburst
• 'Only Daniel' Ricciardo knows of any regrets over Renault move

Given the performance gap between the Enstone squad and the top teams plus the promise shown by Honda, with whom Red Bull will be teaming up with in 2019, Webber really has his doubts over Ricciardo's decision.

"He’s made his bed over there with Renault, which I think is a weird decision, but that’s what he wants to do because he wants a change of environment," he said.

"But it really can test how much he actually is enjoying the sport."