John Mayer has defended Justin Bieber after he cancelled the remainder of his Purpose World Tour.

The 'Free Fallin' hitmaker has praised the 'Love Yourself' singer for knowing it was time to ''call it'' and pull the remaining 14 dates of the tour including a string of shows in North America as well as gigs in Japan, Singapore and The Philippines.

John wrote on Twitter: ''When someone pulls remaining dates of a tour, it means they would have done real damage to themselves if they kept going ...

''We've lost so many great artists lately. I give Justin [a thumbs up] for realizing it was time to call it. You should too. (sic)''

Justin announced he would be cancelling the dates in a post on his website on Monday (24.07.17).

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.''

And now it has been claimed that Justin axed the dates because he is ''exhausted''.

A source said: ''This is a guy who has had 150 shows on this tour, on six continents, over the last year and half, and he's tired. He needed a break and as much as he didn't want to disappoint his fans, the best decision for him was to cancel the remaining tour dates. The tour was just really long and he was exhausted. He doesn't want to let his fans down but they have always had his back.''