Justin Bieber Babysits Kourtney Kardashian's Son Mason Disick

Justin Bieber and Mason Disick have a playdate at the pool. Photo: Instagram

Justin Bieber spent Friday (US time) with none other than Kourtney Kardashian and Scott Disick's son Mason.

Sharing a photo from a pool party of himself with Mason, the Beauty and a Beat singer added, "Mason is cool as a fan."

Mason's grandmother Kris Jenner reposted the same photo and applauded Justin for being the "#bestbabysitterintheworld".

Meanwhile, Mason's dad Scott - who has been battling with alcohol addiction and spent less than a week in a rehab facility in Costa Rica recently - flew to Las Vegas for a club appearance on Friday night.

Justin has been spending a lot of time with the Kardashian family as of late. The 21-year-old star features alongside Kendall Jenner for the April issue of Vogue magazine. The Mario Testino shoot also featured Kendall's best friend Gigi Hadid and Ansel Elgort (Insurgent).