Dwayne Johnson ''fully expects'' Justin and Hailey Bieber to start a family next year.

Hailey, 23, recently became an auntie when her sister Alaia Baldwin welcomed her daughter Iris with her husband Andrew Aronow, and over the weekend, Hailey and her spouse Justin got to meet the new arrival.

The pair both posted pictures with baby Iris, and the snaps caught the attention of actor and former wrestler Dwayne, who said he's now convinced the couple will make fantastic parents one day.

Commenting on a picture posted by Justin, Dwayne wrote: ''This image pretty much seals the deal. Fully expect you and H to have a baby in 2021. (sic)''

The post comes after sources previously said the topic of becoming parents has become a ''very real conversation'' for the couple, who tied the knot in September 2018 and will celebrate two years of marriage next month.

An insider said: ''Justin and Hailey have been talking more and more about wanting to start a family together. Having kids in the near future has become a very real conversation between them.''

And earlier this year, 26-year-old Justin said having children was the ''next step'' in his relationship with Hailey, but insisted he wanted to ''enjoy being married for a little bit'' first.

He said: ''I want to start my own family in due time. I want to enjoy being married for a little bit, go on tour, be married, enjoy travelling with just us, build more of our relationship. I think that it's definitely the next step, for sure.''

The 'Yummy' hitmaker also previously hinted ''babies'' were in his future in his birthday tribute to Hailey in November last year.

He wrote at the time: ''Happy birthday babes. You make me want to be better everyday. The way you live your life is so attractive.. ps you turn me on in every way. next season BABIES. (sic)''

And a few months before, he had spoken about his desire to go on ''daddy daughter dates'', but insisted he wasn't ''hinting at'' anything.

Posting a picture of himself and Hailey on a date in July 2019, he said: ''Love dates with you baby. One day Ill be doing daddy daughter dates. Not hinting at anything soon I'm not in a rush. I just wanna enjoy you by yourself for a while! (sic)''