Toto Wolff has tipped top driver Lewis Hamilton to stay with Mercedes.

Hamilton has a contract with Mercedes until the end of next year, but boss Wolff rates his chances of retaining the triple world champion.

"If you would have asked me the same question one year ago, I would not have been very optimistic, but now it is different," he is quoted as saying by the Irish Independent.

"After five years, this relationship has become so strong in a way that it wasn't last season."

Hamilton is six points behind championship leader Sebastian Vettel going into this weekend's Monaco Grand Prix.