Justin Bieber agreed to appear in David Hasselhoff's new movie as a favour to the actor.

Justin Bieber

Justin Bieber

The 23-year-old singer makes a cameo appearance in 'Killing Hasselhoff' after David agreed to let him drive the 'Knight Rider' car, which features in his popular TV series of the same name.

David shared: "[Justin] is in the very last scene in the movie - although I'm not supposed to mention anything!

"He's a friend of mine, you see. I did him a favour by doing a video that was never released and so he did me a favour by riding in the Knight Rider car at the end of the movie with me - it was quite a surprise."

Justin will feature as the voice of the famous talking car in the new movie, which focuses on a man who goes to dramatic lengths to pay off his debts.

Of the new film, David explained: "I produced the movie. It's a comedy and I'm really proud of it.

"It took about two-and-a-half years to finally get released and now it's coming out on digital on September 18."

David, 65, also offered advice to Justin after he recently announced that he was cancelling the final 14 shows of his Purpose World Tour.

The American actor hailed Justin's maturity and stressed the need for him to "keep moving forward".

Speaking to 'Good Morning Britain', David explained: "You have just got to pick yourself up and keep going forward.

"He's quite young. I just saw him in concert and he is damn good. He is terrific. I saw him backstage afterwards and he has this level of maturity that is really nice."

Justin's tour cancellation was confirmed on Monday (24.07.17) via a post uploaded to his website.

The statement read: "Due to unforeseen circumstances, Justin Bieber will cancel the remainder of the Purpose World Tour concerts. Justin loves his fans and hates to disappoint them. He thanks his fans for the incredible experience of the Purpose World Tour over last 18 months. He is grateful and honoured to have shared that experience with his cast and crew for over 150 successful shows across 6 continents during this run. However, after careful consideration he has decided he will not be performing any further dates. Tickets will be refunded at point of purchase."