Mark Webber admits his former teammate Sebastian Vettel may be "at the crossroads" about his Formula 1 future.

The Australian was asked about the recent speculation that the four-time world champion is considering retirement amid a difficult year at Ferrari, including the threat from Charles Leclerc.

And in his response, the former Red Bull driver can understand Vettel's situation.

"Anything is possible in Formula 1. He is definitely at the crossroads of his career, even mentally," Webber told Austria's Servus TV.

"He has to decide what he wants in the coming years, which is really a fine line to do it and continue to have success."

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An interesting observation he has made, however, is Sebastian's demeanour which suggested something he never would have expected.

"It's confusing because he often still seems hungry and aggressive, then at other times, he's relaxed when he finishes second or third, and I wouldn't expect him to be satisfied with that," Webber stated.

"Only Sebastian can answer that for himself, but one thing is certain and it's that Ferrari also needs to improve."